{"id":233,"date":"2021-12-17T21:43:00","date_gmt":"2021-12-17T21:43:00","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/chapter\/3-minerals\/"},"modified":"2025-01-21T01:03:28","modified_gmt":"2025-01-21T01:03:28","slug":"3-minerals","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/chapter\/3-minerals\/","title":{"raw":"3 Minerals","rendered":"3 Minerals"},"content":{"raw":"[caption id=\"attachment_2752\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cristales_cueva_de_Naica.jpg\"><img class=\"wp-image-2752 size-large\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/Cristales_cueva_de_Naica-1024x683-1.jpg\" alt=\"The crystals are huge!\" width=\"1024\" height=\"683\"><\/a> These selenite (gypsum) crystals, found in The Cave of the Crystals in Naica, Mexico, has some of the largest minerals ever found. The largest crystal found here is 39 feet (12 meters) and 55 tones.[\/caption]\n<h1>3 Minerals<\/h1>\n<strong>KEY<\/strong><b> CONCEPTS<\/b>\n\n<b>At the end of this chapter, students should be able to:<\/b>\n<ul>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Define [pb_glossary id=\"2687\"]mineral[\/pb_glossary].<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the basic structure of the atom.<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Derive basic atomic information from the Periodic Table of [pb_glossary id=\"2700\"]Elements[\/pb_glossary].<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe chemical [pb_glossary id=\"2703\"]bonding[\/pb_glossary] related to [pb_glossary id=\"2687\"]minerals[\/pb_glossary].<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the main ways [pb_glossary id=\"2687\"]minerals[\/pb_glossary] form.<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the [pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary] and how it forms common [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary].<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">List common non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] in [pb_glossary id=\"1919\"]oxide[\/pb_glossary], [pb_glossary id=\"1921\"]sulfide[\/pb_glossary], [pb_glossary id=\"1922\"]sulfate[\/pb_glossary], and [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] groups.<\/span><\/li>\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] using physical properties and identification tables. <\/span><\/li>\n<\/ul>\nThe term \u201c[pb_glossary id=\"2687\"]minerals[\/pb_glossary]\u201d as used in nutrition labels and pharmaceutical products is not the same as a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] in a geological sense. In geology, the classic definition of a <strong>[pb_glossary id=\"2687\"]mineral[\/pb_glossary]<\/strong> is: 1) naturally occurring, 2) inorganic, 3) solid at room [pb_glossary id=\"2689\"]temperature[\/pb_glossary], 4) regular crystal structure, and 5) defined chemical [pb_glossary id=\"2831\"]composition[\/pb_glossary]. Some natural substances technically should not be considered [pb_glossary id=\"2687\"]minerals[\/pb_glossary], but are included by exception. For example, water and mercury are liquid at room [pb_glossary id=\"2689\"]temperature[\/pb_glossary]. Both are considered [pb_glossary id=\"2687\"]minerals[\/pb_glossary] because they were classified before the room-[pb_glossary id=\"2689\"]temperature[\/pb_glossary] rule was accepted as part of the definition. [pb_glossary id=\"1918\"]Calcite[\/pb_glossary] is quite often formed by organic processes, but is considered a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] because it is widely found and geologically important. Because of these discrepancies, the International Mineralogical Association in 1985 amended the definition to: \u201cA [pb_glossary id=\"2687\"]mineral[\/pb_glossary] is an [pb_glossary id=\"2700\"]element[\/pb_glossary] or chemical compound that is normally crystalline and that has been formed as a result of geological processes.\u201d This means that the [pb_glossary id=\"1918\"]calcite[\/pb_glossary] in the shell of a clam is not considered a [pb_glossary id=\"2687\"]mineral[\/pb_glossary]. But once that clam shell undergoes burial, [pb_glossary id=\"2827\"]diagenesis[\/pb_glossary], or other geological processes, then the [pb_glossary id=\"1918\"]calcite[\/pb_glossary] is considered a [pb_glossary id=\"2687\"]mineral[\/pb_glossary]. Typically, substances like [pb_glossary id=\"2856\"]coal[\/pb_glossary], pearl, opal, or [pb_glossary id=\"1947\"]obsidian[\/pb_glossary] that do not fit the definition of [pb_glossary id=\"2687\"]mineral[\/pb_glossary] are called mineraloids.\n\nA <strong>rock<\/strong> is a substance that contains one or more [pb_glossary id=\"2687\"]minerals[\/pb_glossary] or mineraloids. As is discussed in later chapters, there are three types of rocks [pb_glossary id=\"2831\"]composed[\/pb_glossary] of [pb_glossary id=\"2687\"]minerals[\/pb_glossary]: [pb_glossary id=\"2675\"]igneous[\/pb_glossary] (rocks crystallizing from molten material), sedimentary (rocks [pb_glossary id=\"2831\"]composed[\/pb_glossary] of products of [pb_glossary id=\"1204\"]mechanical weathering[\/pb_glossary] (sand, gravel, etc.) and [pb_glossary id=\"2812\"]chemical weathering[\/pb_glossary] (things [pb_glossary id=\"2707\"]precipitated[\/pb_glossary] from [pb_glossary id=\"2705\"]solution[\/pb_glossary]), and [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] (rocks produced by alteration of other rocks by heat and pressure.\n<h2><span style=\"font-weight: 400\">3.1 Chemistry of Minerals<\/span><\/h2>\nRocks are [pb_glossary id=\"2831\"]composed[\/pb_glossary] of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] that have a specific chemical [pb_glossary id=\"2831\"]composition[\/pb_glossary].\u00a0 To understand [pb_glossary id=\"2687\"]mineral[\/pb_glossary] chemistry, it is essential to examine the fundamental unit of all matter, the atom.\n<h3><b>3.1.1 The Atom<\/b><\/h3>\n[caption id=\"attachment_2753\" align=\"alignright\" width=\"283\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.1-Electron_cloud_model_of_atom.jpg\"><img class=\"size-medium wp-image-2753\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/03.1-Electron_cloud_model_of_atom-283x300-1.jpg\" alt=\"Image of atom with defined nucleus and electrons surrounding it in a cloud with concentrations of electrons in energy shells\" width=\"283\" height=\"300\"><\/a> Electron cloud model of the atom[\/caption]\n\nMatter is made of atoms. Atoms consists of subatomic particles\u2014<strong>protons<\/strong>, <strong>neutrons<\/strong>, and <strong>electrons<\/strong>. A simple model of the atom has a central nucleus [pb_glossary id=\"2831\"]composed[\/pb_glossary] of protons, which have positive charges, and neutrons which have no charge. A cloud of negatively charged electrons surrounds the nucleus, the number of electrons equaling the number of protons thus balancing the positive charge of the protons for a neutral atom. Protons and neutrons each have a mass number of 1. The mass of an electron is less than\u00a01\/1000<sup>th<\/sup>\u00a0that of a proton or neutron, meaning most of the atom\u2019s mass is in the nucleus.\n<h3><b>3.1.2 Periodic Table of the Elements<\/b><\/h3>\nMatter is [pb_glossary id=\"2831\"]composed[\/pb_glossary] of [pb_glossary id=\"2700\"]elements[\/pb_glossary] which are atoms that have a specific number of protons in the nucleus. This number of protons is called the <strong>Atomic Number<\/strong> for the [pb_glossary id=\"2700\"]element[\/pb_glossary]. For example, an oxygen atom has 8 protons and an iron atom has 26 protons. An [pb_glossary id=\"2700\"]element[\/pb_glossary] cannot be broken down chemically into a simpler form and retains unique chemical and physical properties. Each [pb_glossary id=\"2700\"]element[\/pb_glossary] behaves in a unique manner in nature. This uniqueness led scientists to develop a periodic table of the [pb_glossary id=\"2700\"]elements[\/pb_glossary], a tabular arrangement of all known [pb_glossary id=\"2700\"]elements[\/pb_glossary] listed in order of their atomic number.\n\n[caption id=\"attachment_2754\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Periodic_Table-02-scaled.jpg\"><img class=\"size-large wp-image-2754\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/Periodic_Table-02-1024x795-1.jpg\" alt=\"The Periodic Table of the Elements showing all elements with their chemical symbols, atomic weight, and atomic number.\" width=\"1024\" height=\"795\"><\/a> The Periodic Table of the Elements[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">The first arrangement of [pb_glossary id=\"2700\"]elements[\/pb_glossary] into a periodic table was done by Dmitri Mendeleev in 1869 using the [pb_glossary id=\"2700\"]elements[\/pb_glossary] known at the time<\/span><span style=\"font-weight: 400\">. In the periodic table, each [pb_glossary id=\"2700\"]element[\/pb_glossary] has a chemical symbol, name, atomic number, and atomic mass. The chemical symbol is an abbreviation for the [pb_glossary id=\"2700\"]element[\/pb_glossary], often derived from a Latin or Greek name for the substance<\/span><span style=\"font-weight: 400\">. The atomic number is the number of protons in the nucleus. The atomic mass is the number of protons and neutrons in the nucleus, each with a mass number of one. Since the mass of electrons is so much less than the protons and neutrons, the atomic mass is effectively the number of protons plus neutrons. <\/span>\n\n[caption id=\"attachment_2755\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3a_Formation_of_Carbon14_from_Nitrogen14.jpg\"><img class=\"size-medium wp-image-2755\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/3.3a_Formation_of_Carbon14_from_Nitrogen14-300x123-1.jpg\" alt=\"\" width=\"300\" height=\"123\"><\/a> Formation of Carbon 14 from Nitrogen 14[\/caption]\n\nThe atomic mass of natural [pb_glossary id=\"2700\"]elements[\/pb_glossary] represents an average mass of the atoms comprising that substance in nature and is usually not a whole number as seen on the periodic table, meaning that an [pb_glossary id=\"2700\"]element[\/pb_glossary] exists in nature with atoms having different numbers of neutrons. The differing number of neutrons affects the mass of an [pb_glossary id=\"2700\"]element[\/pb_glossary] in nature and the atomic mass number represents this average. This gives rise to the concept of\u00a0[pb_glossary id=\"2701\"]isotope[\/pb_glossary]<strong>.\u00a0<\/strong><strong>[pb_glossary id=\"2701\"]Isotopes[\/pb_glossary] <\/strong>are forms of an [pb_glossary id=\"2700\"]element[\/pb_glossary] with the same number of protons but different numbers of neutrons. There are usually several [pb_glossary id=\"2701\"]isotopes[\/pb_glossary] for a particular [pb_glossary id=\"2700\"]element[\/pb_glossary]. For example, 98.9% of carbon atoms have 6 protons and 6 neutrons. This [pb_glossary id=\"2701\"]isotope[\/pb_glossary] of carbon is called carbon-12 (<sup>12<\/sup>C). A few carbon atoms, carbon-13 (<sup>13<\/sup>C), have 6 protons and 7 neutrons. A trace amount of carbon atoms, carbon-14 (<sup>14<\/sup>C), has 6 protons and 8 neutrons.\n\n[caption id=\"attachment_2756\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/elemental-composition-crust.jpg\"><img class=\"size-medium wp-image-2756\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/elemental-composition-crust-300x277-1.jpg\" alt=\"Oxygen and silicon make up 3\/4ths of the chart.\" width=\"300\" height=\"277\"><\/a> Element abundance pie chart for Earth's crust by Callan Bentley.[\/caption]\n\nAmong the 118 known [pb_glossary id=\"2700\"]elements[\/pb_glossary], the heaviest are fleeting human creations known only in high energy particle accelerators, and they decay rapidly. The heaviest naturally occurring [pb_glossary id=\"2700\"]element[\/pb_glossary] is uranium, atomic number 92. The eight most abundant elements in Earth\u2019s [pb_glossary id=\"2575\"]continental crust[\/pb_glossary] are shown in Table 1<span style=\"font-weight: 400\">. These [pb_glossary id=\"2700\"]elements[\/pb_glossary] are found in the most common rock forming [pb_glossary id=\"2687\"]minerals[\/pb_glossary].<\/span>\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n<table style=\"height: 135px\">\n<tbody>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><b>[pb_glossary id=\"2700\"]Element[\/pb_glossary]<\/b><\/td>\n<td style=\"height: 15px;width: 134.797px\"><b>Symbol<\/b><\/td>\n<td style=\"height: 15px;width: 237.703px\"><b>Abundance %<\/b><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Oxygen<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">O<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">47%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Silicon<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Si<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">28%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Aluminum<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Al<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">8%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Iron<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Fe<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">5%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Calcium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Ca<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">4%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Sodium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Na<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Potassium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">K<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Magnesium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">Mg<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">2%<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<em style=\"font-size: 16px;font-weight: 400\">Table 1. Eight Most Abundant [pb_glossary id=\"2700\"]Elements[\/pb_glossary] in the Earth\u2019s [pb_glossary id=\"2575\"]Continental Crust[\/pb_glossary] % by weight (source:\u00a0<a href=\"https:\/\/pubs.usgs.gov\/circ\/1953\/0285\/report.pdf\">USGS<\/a>). All other [pb_glossary id=\"2700\"]elements[\/pb_glossary] are less than 1%.<\/em>\n<h3><b>3.1.3 Chemical Bonding<\/b><\/h3>\n[caption id=\"attachment_2757\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/H2O_2D_labelled.svg_.png\"><img class=\"wp-image-145 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-300x131.png\" alt=\"The hydrogen atoms are on one side, about 105\u00b0 apart.\" width=\"300\" height=\"131\"><\/a> A model of a water molecule, showing the bonds between the hydrogen and oxygen.[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">Most substances on Earth are compounds containing multiple [pb_glossary id=\"2700\"]elements[\/pb_glossary]. Chemical [pb_glossary id=\"2703\"]bonding[\/pb_glossary] describes how these atoms attach with each other to form compounds, such as sodium and chlorine combining to form NaCl, common table salt. Compounds that are held together by\u00a0<\/span>chemical [pb_glossary id=\"2703\"]bonds[\/pb_glossary] are called molecules. Water is a compound of hydrogen and oxygen in which two hydrogen atoms are covalently [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with one oxygen making the water molecule. The oxygen we breathe is formed when one oxygen atom covalently [pb_glossary id=\"2703\"]bonds[\/pb_glossary] with another oxygen atom to make the molecule O<sub>2<\/sub>. The subscript 2 in the chemical formula indicates the molecule contains two atoms of oxygen.\n\nMost [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are also compounds of more than one [pb_glossary id=\"2700\"]element[\/pb_glossary]. The common [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"1918\"]calcite[\/pb_glossary] has the chemical formula CaCO<sub>3<\/sub> indicating the molecule consists of one calcium, one carbon, and three oxygen atoms.\u00a0In [pb_glossary id=\"1918\"]calcite[\/pb_glossary], one carbon and three oxygen atoms are held together by covalent [pb_glossary id=\"2703\"]bonds[\/pb_glossary] to form a <strong>molecular [pb_glossary id=\"3371\"]ion[\/pb_glossary]<\/strong>, called [pb_glossary id=\"1917\"]carbonate[\/pb_glossary], which has a negative charge. Calcium as an <strong>[pb_glossary id=\"3371\"]ion[\/pb_glossary]<\/strong> has a positive charge of plus two. The two oppositely charged ions attract each other and combine to form the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"1918\"]calcite[\/pb_glossary], CaCO3. The name of the chemical compound is calcium [pb_glossary id=\"1917\"]carbonate[\/pb_glossary], where calcium is Ca and [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] refers to the molecular [pb_glossary id=\"3371\"]ion[\/pb_glossary] CO<sub>3<\/sub><sup>-2<\/sup>.\n\nThe [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"2711\"]olivine[\/pb_glossary] has the chemical formula (Mg,Fe)<sub>2<\/sub>SiO<sub>4<\/sub>, in which one silicon and four oxygen atoms are [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with two atoms of either magnesium or iron.\u00a0The comma between iron (Fe) and magnesium (Mg) indicates the two [pb_glossary id=\"2700\"]elements[\/pb_glossary] can occupy the same location in the crystal structure and substitute for one another.\n<h4><i><span style=\"font-weight: 400\">3.1.3.1 Valence and Charge<\/span><\/i><\/h4>\n<span style=\"font-weight: 400\">The electrons around the atom\u2019s nucleus are located in shells representing different energy levels. The outermost shell is called the <strong>valence shell<\/strong>. Electrons in the valence shell are involved in chemical [pb_glossary id=\"2703\"]bonding[\/pb_glossary]. In 1913, Niels Bohr proposed a simple model of the atom that states atoms are more stable when their outermost shell is full<\/span><span style=\"font-weight: 400\">. Atoms of most [pb_glossary id=\"2700\"]elements[\/pb_glossary] thus tend to gain or lose electrons so the outermost or valence shell is full. In Bohr\u2019s model, the innermost shell can have a maximum of two electrons and the second and third shells can have a maximum of eight electrons. <\/span>When the innermost shell is the valence shell, as in the case of hydrogen and helium, it obeys the [pb_glossary id=\"3361\"]octet rule[\/pb_glossary] when it is full with two electrons. For [pb_glossary id=\"2700\"]elements[\/pb_glossary] in higher rows, the [pb_glossary id=\"3361\"]octet rule[\/pb_glossary] of eight electrons in the valence shell applies.\n\n[caption id=\"attachment_2758\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.4_Carbon_dioxide_3D_ball.png\"><img class=\"wp-image-2758 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.4_Carbon_dioxide_3D_ball-300x213-1.png\" alt=\"Carbon dioxide molecule with a carbon ion in the center and two oxygen ions on either side, each sharing two electrons with the carbon.\" width=\"300\" height=\"213\"><\/a> The carbon dioxide molecule. Since Oxygen is -2 and Carbon is +4, the two oxygens bond to the carbon to form a neutral molecule.[\/caption]\n\nThe rows in the periodic table present the [pb_glossary id=\"2700\"]elements[\/pb_glossary] in order of atomic number and the columns organize [pb_glossary id=\"2700\"]elements[\/pb_glossary] with similar characteristics, such as the same number of electrons in their valence shells. Columns are often labeled from left to right with Roman numerals I to VIII, and Arabic numerals 1 through 18. The [pb_glossary id=\"2700\"]elements[\/pb_glossary] in columns I and II have 1 and 2 electrons in their respective valence shells and the [pb_glossary id=\"2700\"]elements[\/pb_glossary] in columns VI and VII have 6 and 7 electrons in their respective valence shells.\n\n<span style=\"font-weight: 400\">In row 3 and column I, sodium (Na) has 11 protons in the nucleus and 11 electrons in three shells\u20142 electrons in the inner shell, 8 electrons in the second shell, and 1 electron in the valence shell. To maintain a full outer shell of 8 electrons per the [pb_glossary id=\"3361\"]octet rule[\/pb_glossary], sodium readily gives up that 1 electron so there are 10 total electrons. With 11 positively charged protons in the nucleus and 10 negatively charged electrons in two shells, sodium when forming chemical [pb_glossary id=\"2703\"]bonds[\/pb_glossary] is an [pb_glossary id=\"3371\"]ion[\/pb_glossary] with an overall net charge of +1<\/span><span style=\"font-weight: 400\">.<\/span>\n\n<span style=\"font-weight: 400\">All [pb_glossary id=\"2700\"]elements[\/pb_glossary] in column I have a single electron in their valence shell and a valence of 1.\u00a0<\/span>These other column I [pb_glossary id=\"2700\"]elements[\/pb_glossary] also readily give up this single valence electron and thus become ions with a +1 charge. [pb_glossary id=\"2700\"]Elements[\/pb_glossary] in column II readily give up 2 electrons and end up as ions with a charge of +2. Note that elements in columns I and II which readily give up their valence electrons, often form bonds with [pb_glossary id=\"2700\"]elements[\/pb_glossary] in columns VI and VII which readily take up these electrons. \u00a0[pb_glossary id=\"2700\"]Elements[\/pb_glossary] in columns 3 through 15 are usually involved in covalent [pb_glossary id=\"2703\"]bonding[\/pb_glossary]. The last column 18 (VIII) contains the <strong>noble gases<\/strong>. These [pb_glossary id=\"2700\"]elements[\/pb_glossary] are chemically inert because the valence shell is already full with 8 electrons, so they do not gain or lose electrons. An example is the noble gas helium which has 2 valence electrons in the first shell. Its valence shell is therefore full. All [pb_glossary id=\"2700\"]elements[\/pb_glossary] in column VIII possess full valence shells and do not form [pb_glossary id=\"2703\"]bonds[\/pb_glossary] with other [pb_glossary id=\"2700\"]elements[\/pb_glossary].\n\n<span style=\"font-weight: 400\">As seen above, an atom with a net positive or negative charge as a result of gaining or losing electrons is called an <strong>[pb_glossary id=\"3371\"]ion[\/pb_glossary]<\/strong>. In general the [pb_glossary id=\"2700\"]elements[\/pb_glossary] on the left side of the table lose electrons and become positive ions, called [pb_glossary id=\"2702\"]cations[\/pb_glossary] because they are attracted to the cathode in an electrical device. The [pb_glossary id=\"2700\"]elements[\/pb_glossary] on the right side tend to gain electrons. These are called [pb_glossary id=\"2704\"]anions[\/pb_glossary] because they are attracted to the anode in an electrical device. The [pb_glossary id=\"2700\"]elements[\/pb_glossary] in the center of the periodic table, columns 3 through 15, do not consistently follow the [pb_glossary id=\"3361\"]octet rule[\/pb_glossary]. These are called transition [pb_glossary id=\"2700\"]elements[\/pb_glossary]. A common example is iron, which has a +2 or +3 charge depending on the [pb_glossary id=\"2818\"]oxidation[\/pb_glossary] state of the [pb_glossary id=\"2700\"]element[\/pb_glossary]. Oxidized Fe<sup>+3<\/sup> carries a +3 charge and reduced Fe<sup>+2<\/sup> is +2. These two different [pb_glossary id=\"2818\"]oxidation[\/pb_glossary] states of iron often impart dramatic colors to rocks containing their [pb_glossary id=\"2687\"]minerals[\/pb_glossary]\u2014the oxidized form producing red colors and the reduced form producing green.<\/span>\n<h4><i><span style=\"font-weight: 400\">3.1.3.2\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Ionic Bonding<\/span><\/i><\/h4>\n[caption id=\"attachment_2759\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03-Sodium-chloride-3D-ionic.png\"><img class=\"size-medium wp-image-2759\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03-Sodium-chloride-3D-ionic-300x284-1.png\" alt=\"Image of crystal model of halite with ions of sodium and chlorine arranged in a cubic structure.\" width=\"300\" height=\"284\"><\/a> Cubic arrangement of Na and Cl in Halite[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">Ionic [pb_glossary id=\"2703\"]bonds[\/pb_glossary], also called electron-transfer [pb_glossary id=\"2703\"]bonds[\/pb_glossary], are formed by the electrostatic attraction between atoms having opposite charges. Atoms of two opposite charges attract each other electrostatically and form an <strong>ionic [pb_glossary id=\"2703\"]bond[\/pb_glossary]<\/strong> in which the positive [pb_glossary id=\"3371\"]ion[\/pb_glossary] transfers its electron (or electrons) to the negative [pb_glossary id=\"3371\"]ion[\/pb_glossary] which takes them up. Through this transfer both atoms thus achieve a full valence shell.\u00a0<\/span>For example one atom of sodium (Na<sup>+1<\/sup>) and one atom of chlorine (Cl<sup>-1<\/sup>) form an ionic [pb_glossary id=\"2703\"]bond[\/pb_glossary] to make the compound sodium chloride (NaCl). This is also known as the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"2844\"]halite[\/pb_glossary] or common table salt. Another example is calcium (Ca<sup>+2<\/sup>) and chlorine (Cl<sup>-1<\/sup>) combining to make the compound calcium chloride (CaCl<sub>2<\/sub>). The subscript 2 indicates two atoms of chlorine are ionically [pb_glossary id=\"2703\"]bonded[\/pb_glossary] to one atom of calcium.\n<h4><i><span style=\"font-weight: 400\">3.1.3.3\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Covalent <\/span><\/i><i><span style=\"font-weight: 400\">Bonding<\/span><\/i><\/h4>\n[caption id=\"attachment_2760\" align=\"alignleft\" width=\"249\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Covalent.svg_.png\"><img class=\"size-medium wp-image-2760\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Covalent.svg_-249x300-1.png\" alt=\"Each atom is sharing electrons.\" width=\"249\" height=\"300\"><\/a> Methane molecule[\/caption]\n\n&nbsp;\n\nIonic [pb_glossary id=\"2703\"]bonds[\/pb_glossary] are usually formed between a <strong>metal<\/strong> and a <strong>nonmetal<\/strong>. Another type, called a covalent or electron-sharing [pb_glossary id=\"2703\"]bond[\/pb_glossary], commonly occurs between nonmetals. Covalent [pb_glossary id=\"2703\"]bonds[\/pb_glossary] share electrons between ions to complete their valence shells. For example, oxygen (atomic number 8) has 8 electrons\u20142 in the inner shell and 6 in the valence shell. Gases like oxygen often form diatomic molecules by sharing valence electrons. In the case of oxygen, two atoms attach to each other and share 2 electrons to fill their valence shells to become the common oxygen molecule we breathe (O<sub>2<\/sub>). Methane (CH<sub>4<\/sub>) is another covalently [pb_glossary id=\"2703\"]bonded[\/pb_glossary] gas. The carbon atom needs 4 electrons and each hydrogen needs 1. Each hydrogen shares its electron with the carbon to form a molecule as shown in the figure.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"17\"]\n\n[caption id=\"attachment_3754\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-149\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 3.1 via this QR Code.[\/caption]\n<h2><span style=\"font-size: 28px\">3.2 Formation of Minerals<\/span><\/h2>\n<span style=\"font-weight: 400\">[pb_glossary id=\"2687\"]Minerals[\/pb_glossary] form when atoms [pb_glossary id=\"2703\"]bond[\/pb_glossary] together in a crystalline arrangement. Three main ways this occurs in nature are: 1) [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] directly from an aqueous (water) [pb_glossary id=\"2705\"]solution[\/pb_glossary] with a [pb_glossary id=\"2689\"]temperature[\/pb_glossary] change, 2) [pb_glossary id=\"2674\"]crystallization[\/pb_glossary] from a [pb_glossary id=\"2672\"]magma[\/pb_glossary] with a [pb_glossary id=\"2689\"]temperature[\/pb_glossary] change, and 3) biological [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] by the action of organisms. <\/span>\n<h3><b> 3.2.1 Precipitation from aqueous solution<\/b><\/h3>\n[caption id=\"attachment_2761\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5_Hard_Water_Calcification.jpg\"><img class=\"size-medium wp-image-2761\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.5_Hard_Water_Calcification-300x200-1.jpg\" alt=\"Encrusted calcium carbonate (lime) deposits on faucent\" width=\"300\" height=\"200\"><\/a> Calcium carbonate deposits from hard water[\/caption]\n\n&nbsp;\n\n[pb_glossary id=\"2705\"]Solutions[\/pb_glossary] consist of ions or molecules, known as solutes, [pb_glossary id=\"2815\"]dissolved[\/pb_glossary] in a medium or solvent. In nature this solvent is usually water. Many [pb_glossary id=\"2687\"]minerals[\/pb_glossary] can be dissolved in water, such as [pb_glossary id=\"2844\"]halite[\/pb_glossary] or table salt, which has the [pb_glossary id=\"2831\"]composition[\/pb_glossary] sodium chloride, NaCl. The Na<sup>+1<\/sup> and Cl<sup>-1<\/sup> ions separate and disperse into the [pb_glossary id=\"2705\"]solution[\/pb_glossary].\n\n<strong>[pb_glossary id=\"2707\"]Precipitation[\/pb_glossary]<\/strong> is the reverse process, in which ions in [pb_glossary id=\"2705\"]solution[\/pb_glossary] come together to form solid [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. [pb_glossary id=\"2707\"]Precipitation[\/pb_glossary] is dependent on the concentration of ions in [pb_glossary id=\"2705\"]solution[\/pb_glossary] and other factors such as [pb_glossary id=\"2689\"]temperature[\/pb_glossary] and pressure. The point at which a solvent cannot hold any more solute is called [pb_glossary id=\"2706\"]saturation[\/pb_glossary]. [pb_glossary id=\"2707\"]Precipitation[\/pb_glossary] can occur when the [pb_glossary id=\"2689\"]temperature[\/pb_glossary] of the [pb_glossary id=\"2705\"]solution[\/pb_glossary] [pb_glossary id=\"3119\"]falls[\/pb_glossary], when the solute evaporates, or with changing chemical conditions in the [pb_glossary id=\"2705\"]solution[\/pb_glossary]. An example of [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] in our homes is when water evaporates and leaves behind a rind of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] on faucets, shower heads, and drinking glasses.\n\nIn nature, changes in environmental conditions may cause the [pb_glossary id=\"2687\"]minerals[\/pb_glossary] [pb_glossary id=\"2815\"]dissolved[\/pb_glossary] in water to form [pb_glossary id=\"2703\"]bonds[\/pb_glossary] and grow into crystals or cement grains of [pb_glossary id=\"2678\"]sediment[\/pb_glossary] together. In Utah, deposits of [pb_glossary id=\"2846\"]tufa[\/pb_glossary] formed from [pb_glossary id=\"2687\"]mineral[\/pb_glossary]-rich springs that emerged into the [pb_glossary id=\"1700\"]ice age[\/pb_glossary] Lake Bonneville. Now exposed in dry valleys, this porous [pb_glossary id=\"2846\"]tufa[\/pb_glossary] was a natural insulation used by pioneers to build their homes with a natural protection against summer heat and winter cold. The [pb_glossary id=\"2847\"]travertine[\/pb_glossary] [pb_glossary id=\"3162\"]terraces[\/pb_glossary] at Mammoth Hot Springs in Yellowstone Park are another example formed by [pb_glossary id=\"1918\"]calcite[\/pb_glossary] [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] at the edges of the shallow [pb_glossary id=\"3174\"]spring[\/pb_glossary]-fed ponds.\n\n[caption id=\"attachment_2762\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.6_1200px-Bonneville_Salt_Flats.jpg\"><img class=\"size-medium wp-image-2762\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.6_1200px-Bonneville_Salt_Flats-300x197-1.jpg\" alt=\"The Bonneville Salt Flats of Utah\" width=\"300\" height=\"197\"><\/a> The Bonneville Salt Flats of Utah[\/caption]\n\n<span style=\"font-weight: 400\">Another example of [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] occurs in the Great Salt Lake, Utah, where the concentration of sodium chloride and other salts is nearly eight times greater than in the world\u2019s oceans <\/span><span style=\"font-weight: 400\">[zotpressInText item=\"{DU5CMSHJ}\" format=\"%num%\" brackets=\"yes\"]<\/span><span style=\"font-weight: 400\">.\u00a0<\/span>[pb_glossary id=\"3134\"]Streams[\/pb_glossary] carry salt ions into the lake from the surrounding mountains. With no other outlet, the water in the lake evaporates and the concentration of salt increases until [pb_glossary id=\"2706\"]saturation[\/pb_glossary] is reached and the [pb_glossary id=\"2687\"]minerals[\/pb_glossary] [pb_glossary id=\"2707\"]precipitate[\/pb_glossary] out as [pb_glossary id=\"2678\"]sediments[\/pb_glossary]. Similar salt deposits include [pb_glossary id=\"2844\"]halite[\/pb_glossary] and other precipitates, and occur in other lakes like Mono Lake in California and the Dead Sea.\n<h3><b>3.2.2 Crystallization from Magma<\/b><\/h3>\n[caption id=\"attachment_2763\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5a_Pahoehoe_toe.jpg\"><img class=\"size-medium wp-image-2763\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.5a_Pahoehoe_toe-300x188-1.jpg\" alt=\"A lava flow\" width=\"300\" height=\"188\"><\/a> Lava, magma at the earth\u2019s surface[\/caption]\n\n&nbsp;\n\nHeat is energy that causes atoms in substances to vibrate. [pb_glossary id=\"2689\"]Temperature[\/pb_glossary] is a measure of the intensity of the vibration. If the vibrations are violent enough, chemical [pb_glossary id=\"2703\"]bonds[\/pb_glossary] are broken and the crystals melt releasing the ions into the melt. [pb_glossary id=\"2672\"]Magma[\/pb_glossary] is molten rock with freely moving ions. When [pb_glossary id=\"2672\"]magma[\/pb_glossary] is emplaced at depth or extruded onto the surface (then called [pb_glossary id=\"2673\"]lava[\/pb_glossary]), it starts to cool and [pb_glossary id=\"2687\"]mineral[\/pb_glossary] crystals can form.\n<h3><b>3.2.3 Precipitation by Organisms<\/b><\/h3>\n[caption id=\"attachment_2764\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.8_Ammonite_Asteroceras.jpg\"><img class=\"size-full wp-image-2764\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.8_Ammonite_Asteroceras.jpg\" alt=\"Shell of an ammonite, an extinct cephalopod, with a spiral shell in a plane.\" width=\"300\" height=\"225\"><\/a> Ammonite shell made of calcium carbonate[\/caption]\n\n<span style=\"font-size: 1em\">Many organisms build bones, shells, and body coverings by extracting ions from water and precipitating [pb_glossary id=\"2687\"]minerals[\/pb_glossary] biologically. The most common [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"2707\"]precipitated[\/pb_glossary] by organisms is [pb_glossary id=\"1918\"]calcite[\/pb_glossary], or calcium [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] (CaCO3). [pb_glossary id=\"1918\"]Calcite[\/pb_glossary] is often [pb_glossary id=\"2707\"]precipitated[\/pb_glossary] by organisms as a [pb_glossary id=\"3362\"]polymorph[\/pb_glossary] called aragonite. <\/span><strong style=\"font-size: 1em\">[pb_glossary id=\"3362\"]Polymorphs[\/pb_glossary]<\/strong><span style=\"font-size: 1em\"> are crystals with the same chemical formula but different crystal structures. [pb_glossary id=\"2883\"]Marine[\/pb_glossary] invertebrates such as corals and clams [pb_glossary id=\"2707\"]precipitate[\/pb_glossary] aragonite or [pb_glossary id=\"1918\"]calcite[\/pb_glossary] for their shells and structures. Upon death, their hard parts accumulate on the [pb_glossary id=\"2885\"]ocean floor[\/pb_glossary] as [pb_glossary id=\"2678\"]sediments[\/pb_glossary], and eventually may become the [pb_glossary id=\"2683\"]sedimentary rock[\/pb_glossary] [pb_glossary id=\"2851\"]limestone[\/pb_glossary]. Though [pb_glossary id=\"2851\"]limestone[\/pb_glossary] can form inorganically, the vast majority is formed by this biological process. Another example is [pb_glossary id=\"2883\"]marine[\/pb_glossary] organisms called radiolaria, which are zooplankton that [pb_glossary id=\"2707\"]precipitate[\/pb_glossary] silica for their microscopic external shells. When the organisms die, the shells accumulate on the [pb_glossary id=\"2885\"]ocean floor[\/pb_glossary] and can form the [pb_glossary id=\"2683\"]sedimentary rock[\/pb_glossary] [pb_glossary id=\"2849\"]chert[\/pb_glossary]. An example of biologic [pb_glossary id=\"2707\"]precipitation[\/pb_glossary] from the [pb_glossary id=\"2222\"]vertebrate[\/pb_glossary] world is bone, which is [pb_glossary id=\"2831\"]composed[\/pb_glossary] mostly of a type of apatite, a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] in the [pb_glossary id=\"1923\"]phosphate[\/pb_glossary] group. The apatite found in bones contains calcium and water in its structure and is called hydroxycarbonate apatite, Ca<\/span><sub>5<\/sub><span style=\"font-size: 1em\">(PO<\/span><sub>4<\/sub><span style=\"font-size: 1em\">)<\/span><sub>3<\/sub><span style=\"font-size: 1em\">(OH).\u00a0 As mentioned above, such substances are not technically [pb_glossary id=\"2687\"]minerals[\/pb_glossary] until the organism dies and these hard parts become [pb_glossary id=\"2176\"]fossils[\/pb_glossary].<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"18\"]\n\n[caption id=\"attachment_3753\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-154\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 3.2 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">3.3 Silicate Minerals<\/span><\/h2>\n[caption id=\"attachment_2765\" align=\"alignright\" width=\"256\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedron.gif\"><img class=\"size-full wp-image-2765\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tetrahedron.gif\" alt=\"It is a pyramid shape with a triangular base\" width=\"256\" height=\"256\"><\/a> Rotating animation of a tetrahedra[\/caption]\n\n[pb_glossary id=\"2687\"]Minerals[\/pb_glossary] are categorized based on their [pb_glossary id=\"2831\"]composition[\/pb_glossary] and structure. [pb_glossary id=\"2709\"]Silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are built around a molecular [pb_glossary id=\"3371\"]ion[\/pb_glossary] called the <strong>[pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary]<\/strong>. A tetrahedron has a pyramid-like shape with four sides and four corners.\u00a0[pb_glossary id=\"2709\"]Silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] form the largest group of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] on Earth, comprising the vast majority of the Earth\u2019s [pb_glossary id=\"2586\"]mantle[\/pb_glossary] and [pb_glossary id=\"2580\"]crust[\/pb_glossary]. Of the nearly four thousand known [pb_glossary id=\"2687\"]minerals[\/pb_glossary] on Earth, most are rare. There are only a few that make up most of the rocks likely to be encountered by surface dwelling creatures like us. These are generally called the <strong>rock-forming [pb_glossary id=\"2687\"]minerals[\/pb_glossary]<\/strong>.\n\n[caption id=\"attachment_2766\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.10_Tetrahedron.jpg\"><img class=\"size-medium wp-image-2766\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.10_Tetrahedron-300x300-1.jpg\" alt=\"Model of silicon-oxygen tetrahedron of ping pong balls with a tiny silicon ion in the space in the middle of the four large balls\" width=\"300\" height=\"300\"><\/a> Ping pong ball model of tetrahedron: balls are oxygen, lead sinker in center is silicon[\/caption]\n\nThe [pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary] (SiO<sub>4<\/sub>) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. Each oxygen [pb_glossary id=\"3371\"]ion[\/pb_glossary] has a -2 charge and the silicon [pb_glossary id=\"3371\"]ion[\/pb_glossary] has a +4 charge. The silicon [pb_glossary id=\"3371\"]ion[\/pb_glossary] shares one of its four valence electrons with each of the four oxygen ions in a covalent [pb_glossary id=\"2703\"]bond[\/pb_glossary] to create a symmetrical geometric four-sided pyramid figure. Only half of the oxygen\u2019s valence electrons are shared, giving the [pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary] an ionic charge of -4. This [pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary] forms bonds with many other combinations of ions to form the large group of [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary].\n\n[caption id=\"attachment_2767\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.11_Tetrahedron_open.jpg\"><img class=\"size-medium wp-image-2767\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.11_Tetrahedron_open-300x255-1.jpg\" alt=\"Top ball removed showing the tiny silicon ion in the center\" width=\"300\" height=\"255\"><\/a> The silicon ion in the center of the tetrahedron[\/caption]\n\n<span style=\"font-weight: 400\">The silicon [pb_glossary id=\"3371\"]ion[\/pb_glossary] is much smaller than the oxygen ions (see the figures) and fits into a small space in the center of the four large oxygen ions, seen if the top ball is removed (as shown in the figure to the right). <\/span><span style=\"font-weight: 400\">Because only one of the valence electrons of the corner oxygens is shared, the [pb_glossary id=\"2710\"]silicon-oxygen tetrahedron[\/pb_glossary] has chemically active corners available to form [pb_glossary id=\"2703\"]bonds[\/pb_glossary] with other [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary] or other positively charged ions such as Al<\/span><sub><span style=\"font-weight: 400\">+3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">+2,+3<\/span><\/sub><span style=\"font-weight: 400\">, Mg<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">, K<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, Na<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, and Ca<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">. Depending on many factors, such as the original [pb_glossary id=\"2672\"]magma[\/pb_glossary] chemistry, [pb_glossary id=\"2710\"]silica-oxygen tetrahedra[\/pb_glossary] can combine with other tetrahedra in several different configurations. For example, tetrahedra can be isolated, attached in chains, sheets, or three dimensional structures. These combinations and others create the chemical structure in which positively charged ions can be inserted for unique chemical compositions forming [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] groups. \u00a0\u00a0<\/span>\n<h3><b>3.3.1 The dark ferromagnesian silicates<\/b><\/h3>\n&nbsp;\n\n[caption id=\"attachment_2768\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.12_Peridot_in_basalt.jpg\"><img class=\"size-medium wp-image-2768\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.12_Peridot_in_basalt-300x225-1.jpg\" alt=\"Many small crystall of the green mineral olivine in a mass of basalt\" width=\"300\" height=\"225\"><\/a> Olivine crystals in basalt[\/caption]\n\n<span style=\"font-size: 14pt\"><b>The [pb_glossary id=\"2711\"]Olivine[\/pb_glossary] Family<\/b><\/span>\n\n[pb_glossary id=\"2711\"]Olivine[\/pb_glossary] is the primary [pb_glossary id=\"2687\"]mineral[\/pb_glossary] component in [pb_glossary id=\"2586\"]mantle[\/pb_glossary] rock such as [pb_glossary id=\"2588\"]peridotite[\/pb_glossary] and [pb_glossary id=\"1961\"]basalt[\/pb_glossary]. It is characteristically green when not weathered. The chemical formula is (Fe,Mg)<sub>2<\/sub>SiO<sub>4<\/sub>. As previously described, the comma between iron (Fe) and magnesium (Mg) indicates these two [pb_glossary id=\"2700\"]elements[\/pb_glossary] occur in a [pb_glossary id=\"2708\"]solid solution[\/pb_glossary].\u00a0<span style=\"font-weight: 400\">Not to be confused with a liquid [pb_glossary id=\"2705\"]solution[\/pb_glossary], a [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] occurs when two or more [pb_glossary id=\"2700\"]elements[\/pb_glossary] have similar properties and can freely substitute for each other in the same location in the crystal structure.<\/span>\n\n[caption id=\"attachment_2769\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.13_Atomic_structure_of_olivine_1.png\"><img class=\"size-full wp-image-2769\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.13_Atomic_structure_of_olivine_1.png\" alt=\"Tetrahedral structure of olivine showing the independent tetrahedra connected together by anions of iron and\/or magnesium.\" width=\"300\" height=\"258\"><\/a> Tetrahedral structure of olivine[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"2711\"]Olivine[\/pb_glossary] is referred to as a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] family because of the ability of iron and magnesium to substitute for each other. Iron and magnesium in the [pb_glossary id=\"2711\"]olivine[\/pb_glossary] family indicates a [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] forming a compositional series within the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] group which can form crystals of all iron as one end member and all mixtures of iron and magnesium in between to all magnesium at the other end member. Different [pb_glossary id=\"2687\"]mineral[\/pb_glossary] names are applied to compositions between these end members.\u00a0 In the [pb_glossary id=\"2711\"]olivine[\/pb_glossary] series of [pb_glossary id=\"2687\"]minerals[\/pb_glossary], the iron and magnesium ions in the [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] are about the same size and charge, so either atom can fit into the same location in the growing crystals. Within the cooling [pb_glossary id=\"2672\"]magma[\/pb_glossary], the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] crystals continue to grow until they solidify into [pb_glossary id=\"2675\"]igneous rock[\/pb_glossary]. The relative amounts of iron and magnesium in the parent [pb_glossary id=\"2672\"]magma[\/pb_glossary] determine which [pb_glossary id=\"2687\"]minerals[\/pb_glossary] in the series form. Other rarer [pb_glossary id=\"2700\"]elements[\/pb_glossary] with similar properties to iron or magnesium, like manganese (Mn), can substitute into the [pb_glossary id=\"2711\"]olivine[\/pb_glossary] crystalline structure in small amounts. Such ionic substitutions in [pb_glossary id=\"2687\"]mineral[\/pb_glossary] crystals give rise to the great variety of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and are often responsible for differences in color and other properties within a group or family of [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. [pb_glossary id=\"2711\"]Olivine[\/pb_glossary] has a pure iron end-member (called fayalite) and a pure magnesium end-member (called forsterite). Chemically, [pb_glossary id=\"2711\"]olivine[\/pb_glossary] is mostly silicon, oxygen, iron, and magnesium and therefore is grouped among the dark-colored <\/span>ferromagnesian<span style=\"font-weight: 400\"> (iron=ferro, magnesium=magnesian) or <strong>[pb_glossary id=\"1956\"]mafic[\/pb_glossary]<\/strong> [pb_glossary id=\"2687\"]minerals[\/pb_glossary], a contraction of their chemical symbols Ma and Fe. [pb_glossary id=\"1956\"]Mafic[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are also referred to as dark-colored ferromagnesian [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. <em>Ferro<\/em> means iron and <em>magnesian<\/em> refers to magnesium. Ferromagnesian [pb_glossary id=\"2709\"]silicates[\/pb_glossary] tend to be more dense than non-ferromagnesian [pb_glossary id=\"2709\"]silicates[\/pb_glossary]. This difference in density ends up being important in controlling the behavior of the [pb_glossary id=\"2675\"]igneous[\/pb_glossary] rocks that are built from these [pb_glossary id=\"2687\"]minerals[\/pb_glossary]: whether a [pb_glossary id=\"2576\"]tectonic[\/pb_glossary] [pb_glossary id=\"2591\"]plate[\/pb_glossary] [pb_glossary id=\"2602\"]subducts[\/pb_glossary] or not is largely governed by the density of its rocks, which are in turn controlled by the density of the [pb_glossary id=\"2687\"]minerals[\/pb_glossary] that comprise them.<\/span>\n\nThe crystal structure of [pb_glossary id=\"2711\"]olivine[\/pb_glossary] is built from independent [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary]. [pb_glossary id=\"2687\"]Minerals [\/pb_glossary]with independent tetrahedral structures are called neosilicates (or orthosilicates). In addition to [pb_glossary id=\"2711\"]olivine[\/pb_glossary], other common neosilicate [pb_glossary id=\"2687\"]minerals[\/pb_glossary] include garnet, topaz, kyanite, and [pb_glossary id=\"2175\"]zircon[\/pb_glossary].\n\nTwo other similar arrangements of tetrahedra are close in structure to the neosilicates and [pb_glossary id=\"2938\"]grade[\/pb_glossary] toward the next group of [pb_glossary id=\"2687\"]minerals[\/pb_glossary], the pyroxenes. In a variation on independent tetrahedra called sorosilicates, there are [pb_glossary id=\"2687\"]minerals[\/pb_glossary] that share one oxygen between two tetrahedra, and include [pb_glossary id=\"2687\"]minerals[\/pb_glossary] like pistachio-green epidote, a gemstone. Another variation are the cyclosilicates, which as the name suggests, consist of tetrahedral rings, and include gemstones such as beryl, emerald, aquamarine, and tourmaline\n<h3><b>3.3.2 Pyroxene Family<\/b><\/h3>\n&nbsp;\n\n[caption id=\"attachment_2770\" align=\"aligncenter\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"300\" height=\"231\"><\/a> Crystals of diopside, a member of the pyroxene family[\/caption]\n\n&nbsp;\n\n[caption id=\"attachment_2771\" align=\"alignright\" width=\"70\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Pyroxen-chain.png\"><img class=\"wp-image-2771\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.15_Pyroxen-chain.png\" alt=\"Single chain of tetrahedra in pyroxene, alternating with adjacent corner oxygens bonded. The outer corners are active to bond with other anions.\" width=\"70\" height=\"517\"><\/a> Single chain tetrahedral structure in pyroxene[\/caption]\n\n[pb_glossary id=\"2712\"]Pyroxene[\/pb_glossary] is another family of dark ferromagnesian [pb_glossary id=\"2687\"]minerals[\/pb_glossary], typically black or dark green in color. Members of the [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary] family have a complex chemical [pb_glossary id=\"2831\"]composition[\/pb_glossary] that includes iron, magnesium, aluminum, and other [pb_glossary id=\"2700\"]elements[\/pb_glossary] [pb_glossary id=\"2703\"]bonded[\/pb_glossary] to polymerized [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary]. <strong>Polymers<\/strong> are chains, sheets, or three-dimensional structures, and are formed by multiple tetrahedra covalently [pb_glossary id=\"2703\"]bonded[\/pb_glossary] via their corner oxygen atoms. Pyroxenes are commonly found in [pb_glossary id=\"1956\"]mafic[\/pb_glossary] [pb_glossary id=\"2675\"]igneous[\/pb_glossary] rocks such as [pb_glossary id=\"2588\"]peridotite[\/pb_glossary], [pb_glossary id=\"1961\"]basalt[\/pb_glossary], and [pb_glossary id=\"1964\"]gabbro[\/pb_glossary], as well as [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] rocks like eclogite and blue [pb_glossary id=\"2929\"]schist[\/pb_glossary].\n\nPyroxenes are built from long, single chains of polymerized [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary] in which tetrahedra share two corner oxygens. The silica chains are [pb_glossary id=\"2703\"]bonded[\/pb_glossary] together into the crystal structures by metal cations. A common member of the [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary] family is augite, itself containing several [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] series with a complex chemical formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)<sub>2<\/sub>O<sub>6<\/sub> that gives rise to a number of individual [pb_glossary id=\"2687\"]mineral[\/pb_glossary] names.\n\nThis single-chain crystalline structure [pb_glossary id=\"2703\"]bonds[\/pb_glossary] with many [pb_glossary id=\"2700\"]elements[\/pb_glossary], which can also freely substitute for each other. The generalized chemical [pb_glossary id=\"2831\"]composition[\/pb_glossary] for [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary] is XZ(Al,Si)<sub>2<\/sub>O<sub>6<\/sub>. X represents the ions Na, Ca, Mg, or Fe, and Z represents Mg, Fe, or Al. These ions have similar ionic sizes, which allows many possible substitutions among them. Although the [pb_glossary id=\"2702\"]cations[\/pb_glossary] may freely substitute for each other in the crystal, they carry different ionic charges that must be balanced out in the final crystalline structure. For example Na has a charge of +1, but Ca has charge of +2. If a Na<sup>+<\/sup> [pb_glossary id=\"3371\"]ion[\/pb_glossary] substitutes for a Ca<sup>+2<\/sup> [pb_glossary id=\"3371\"]ion[\/pb_glossary], it creates an unequal charge that must be balanced by other ionic substitutions elsewhere in the crystal. Note that ionic size is more important than ionic charge for substitutions to occur in [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] series in crystals.\n<h3><\/h3>\n<h3><b>3.3.3 Amphibole Family<\/b><\/h3>\n[caption id=\"attachment_2773\" align=\"alignleft\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Orthoclase_Hornblende.jpg\"><img class=\"wp-image-2773\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.15_Orthoclase_Hornblende-300x300-1.jpg\" alt=\"A crystal of orthoclase (potassium feldspar) wth elongated dark crystals of hornblende\" width=\"200\" height=\"200\"><\/a> Elongated crystals of hornblende in orthoclase[\/caption]\n\n&nbsp;\n\n[caption id=\"attachment_2772\" align=\"alignright\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.16_Amphibole.jpg\"><img class=\"wp-image-2772\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.16_Amphibole-300x236-1.jpg\" alt=\"Black crystals of hornblende\" width=\"200\" height=\"157\"><\/a> Hornblende crystals[\/caption]\n\n[pb_glossary id=\"2713\"]Amphibole[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are built from polymerized double silica chains and they are also referred to as inosilicates. Imagine two [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary] chains that connect together by sharing a third oxygen on each tetrahedra.\u00a0 Amphiboles are usually found in [pb_glossary id=\"2675\"]igneous[\/pb_glossary] and [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] rocks and typically have a long-bladed <strong>[pb_glossary id=\"1928\"]crystal habit[\/pb_glossary]<\/strong>. The most common [pb_glossary id=\"2713\"]amphibole[\/pb_glossary], hornblende, is usually black; however, they come in a variety of colors depending on their chemical [pb_glossary id=\"2831\"]composition[\/pb_glossary]. The [pb_glossary id=\"2684\"]metamorphic rock[\/pb_glossary], amphibolite, is primarily [pb_glossary id=\"2831\"]composed[\/pb_glossary] of [pb_glossary id=\"2713\"]amphibole[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary].\n\n[caption id=\"attachment_2774\" align=\"alignleft\" width=\"79\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.17_Tremolite-chain.png\"><img class=\"size-medium wp-image-2774\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.17_Tremolite-chain-79x300-1.png\" alt=\"Double chain structure of amphibole; two single chains laying together with the inner corners of each tetrahedron bonded and the outer cornera active to bond with anions\" width=\"79\" height=\"300\"><\/a> Double chain structure[\/caption]\n\n&nbsp;\n\nAmphiboles are [pb_glossary id=\"2831\"]composed[\/pb_glossary] of iron, magnesium, aluminum, and other [pb_glossary id=\"2702\"]cations[\/pb_glossary] [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary]. These dark ferromagnesian [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are commonly found in [pb_glossary id=\"1964\"]gabbro[\/pb_glossary], baslt, [pb_glossary id=\"1963\"]diorite[\/pb_glossary], and often form the black specks in [pb_glossary id=\"1962\"]granite[\/pb_glossary]. Their chemical formula is very complex and generally written as (RSi<sub>4<\/sub>O<sub>11<\/sub>)<sub>2<\/sub>, where R represents many different [pb_glossary id=\"2702\"]cations[\/pb_glossary]. For example, it can also be written more exactly as AX<sub>2<\/sub>Z<sub>5<\/sub>((Si,Al,Ti)<sub>8<\/sub>O<sub>22<\/sub>)(OH,F,Cl,O)<sub>2<\/sub>. In this formula A may be Ca, Na, K, Pb, or blank; X equals Li, Na, Mg, Fe, Mn, or Ca; and Z is Li, Na, Mg, Fe, Mn, Zn, Co, Ni, Al, \u00a0Cr, Mn, V, Ti, or Zr. The substitutions create a wide variety of colors such as green, black, colorless, white, yellow, blue, or brown. [pb_glossary id=\"2713\"]Amphibole[\/pb_glossary] crystals can also include hydroxide ions (OH<sup>-<\/sup>)<sup>,<\/sup> which occurs from an interaction between the growing [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and water [pb_glossary id=\"2815\"]dissolved[\/pb_glossary] in [pb_glossary id=\"2672\"]magma[\/pb_glossary].\n<h3><\/h3>\n<h3><\/h3>\n<h3><strong>3.3.4 Sheet Silicates<\/strong><\/h3>\n[caption id=\"attachment_2775\" align=\"alignleft\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany.jpg\"><img class=\"wp-image-2775\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany-300x225-1.jpg\" alt=\"Dark brown crystals of biotite mica showing sheet-like habit\" width=\"200\" height=\"150\"><\/a> Sheet crystals of biotite mica[\/caption]\n\n[caption id=\"attachment_3637\" align=\"alignright\" width=\"250\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicaSheetUSGOV.jpg\"><img class=\"wp-image-166\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-300x226.jpg\" alt=\"Crystal of muscovite mica showing sheet structure of the mineral\" width=\"250\" height=\"188\"><\/a> Crystal of muscovite mica[\/caption]\n\nSheet [pb_glossary id=\"2709\"]silicates[\/pb_glossary] are built from tetrahedra which share all three of their bottom corner oxygens thus forming sheets of tetrahedra with their top corners available for [pb_glossary id=\"2703\"]bonding[\/pb_glossary] with other atoms. Micas and clays are common types of sheet [pb_glossary id=\"2709\"]silicates[\/pb_glossary], also known as phyllosilicates. [pb_glossary id=\"1914\"]Mica[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are usually found in [pb_glossary id=\"2675\"]igneous[\/pb_glossary] and [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] rocks, while clay [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are more often found in sedimentary rocks. Two frequently found micas are dark-colored [pb_glossary id=\"1914\"]biotite[\/pb_glossary], frequently found in [pb_glossary id=\"1962\"]granite[\/pb_glossary], and light-colored [pb_glossary id=\"1914\"]muscovite[\/pb_glossary], found in the [pb_glossary id=\"2684\"]metamorphic rock[\/pb_glossary] called [pb_glossary id=\"2929\"]schist[\/pb_glossary].\n\n[caption id=\"attachment_2777\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.20_Silicate-sheet-3D-polyhedra.png\"><img class=\"size-medium wp-image-2777\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.20_Silicate-sheet-3D-polyhedra-300x197-1.png\" alt=\"Continuous sheets of tetradedra with all three base corners bonded to each other; the top corner active to bond with anions\" width=\"300\" height=\"197\"><\/a> Sheet structure of mica[\/caption]\n\nChemically, sheet [pb_glossary id=\"2709\"]silicates[\/pb_glossary] usually contain silicon and oxygen in a 2:5 ratio (Si<sub>4<\/sub>O<sub>10<\/sub>). Micas contain mostly silica, aluminum, and potassium. [pb_glossary id=\"1914\"]Biotite[\/pb_glossary] [pb_glossary id=\"1914\"]mica[\/pb_glossary] has more iron and magnesium and is considered a ferromagnesian [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary]. [pb_glossary id=\"1914\"]Muscovite[\/pb_glossary] micas belong to the [pb_glossary id=\"1954\"]felsic[\/pb_glossary] [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. [pb_glossary id=\"1954\"]Felsic[\/pb_glossary] is a contraction formed from [pb_glossary id=\"1916\"]feldspar[\/pb_glossary], the dominant [pb_glossary id=\"2687\"]mineral[\/pb_glossary] in [pb_glossary id=\"1954\"]felsic[\/pb_glossary] rocks.\n\n[caption id=\"attachment_2778\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.21_Crystal-structure-of-mica.jpg\"><img class=\"size-medium wp-image-2778\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.21_Crystal-structure-of-mica-300x300-1.jpg\" alt=\"Diagram of mica crystal structure with the sheets of tetrahedra inverted onto each other into sandwiches with the active corners bonded with anions and the sandwiches connected together with large potassium ions that form weak bonds easily separated so the crystal comes apart into sheets.\" width=\"300\" height=\"300\"><\/a> Crystal structure of a mica[\/caption]\n\n[caption id=\"attachment_2779\" align=\"alignright\" width=\"296\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Illmenite-mica-sandwich.jpg\"><img class=\"size-medium wp-image-2779\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Illmenite-mica-sandwich-296x300-1.jpg\" alt=\"Silica sheets layered in mica like bread and hjam in a stack of sandwiches\" width=\"296\" height=\"300\"><\/a> Mica \"silica sandwich\" structure[\/caption]\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\nThe illustration of the crystalline structure of [pb_glossary id=\"1914\"]mica[\/pb_glossary] shows the corner O atoms [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with K, Al, Mg, Fe, and Si atoms, forming polymerized sheets of linked tetrahedra, with an octahedral layer of Fe, Mg, or Al, between them.\u00a0 The yellow potassium ions form Van der Waals [pb_glossary id=\"2703\"]bonds[\/pb_glossary] (attraction and repulsion between atoms, molecules, and surfaces) and hold the sheets together. Van der Waals [pb_glossary id=\"2703\"]bonds[\/pb_glossary] differ from\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Covalent_bond\">covalent<\/a>\u00a0and\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Ionic_bond\">ionic<\/a>\u00a0[pb_glossary id=\"2703\"]bonds[\/pb_glossary], and exist here between the sandwiches, holding them together into a [pb_glossary id=\"3213\"]stack[\/pb_glossary] of sandwiches. The Van der Waals [pb_glossary id=\"2703\"]bonds[\/pb_glossary] are weak compared to the [pb_glossary id=\"2703\"]bonds[\/pb_glossary] within the sheets, allowing the sandwiches to be separated along the potassium layers. This gives [pb_glossary id=\"1914\"]mica[\/pb_glossary] its characteristic property of easily cleaving into sheets.\n\n[caption id=\"attachment_2780\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.22_Kaolinite-structure.jpg\"><img class=\"size-medium wp-image-2780\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.22_Kaolinite-structure-300x244-1.jpg\" alt=\"Crystal structure of kaolinite, a clay mineral with sheet structure like mica except that the\" width=\"300\" height=\"244\"><\/a> Structure of kaolinite[\/caption]\n\nClays [pb_glossary id=\"2687\"]minerals[\/pb_glossary] occur in [pb_glossary id=\"2678\"]sediments[\/pb_glossary] formed by the [pb_glossary id=\"2676\"]weathering[\/pb_glossary] of rocks and are another family of [pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] with a tetrahedral sheet structure. Clay [pb_glossary id=\"2687\"]minerals[\/pb_glossary] form a complex family, and are an important component of many sedimentary rocks. Other sheet [pb_glossary id=\"2709\"]silicates[\/pb_glossary] include serpentine and chlorite, found in [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] rocks.\n\nClay [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are [pb_glossary id=\"2831\"]composed[\/pb_glossary] of hydrous aluminum [pb_glossary id=\"2709\"]silicates[\/pb_glossary]. One type of clay, kaolinite, has a structure like an open-faced sandwich, with the bread being a single layer of [pb_glossary id=\"2710\"]silicon-oxygen tetrahedra[\/pb_glossary] and a layer of aluminum as the spread in an octahedral configuration with the top oxygens of the sheets.\n<h3><b>3.3.5 Framework Silicates<\/b><\/h3>\n[caption id=\"attachment_2829\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a> Freely growing quartz crystals showing crystal faces[\/caption]\n\n&nbsp;\n\n[pb_glossary id=\"1915\"]Quartz[\/pb_glossary] and [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] are the two most abundant [pb_glossary id=\"2687\"]minerals[\/pb_glossary] in the [pb_glossary id=\"2575\"]continental crust[\/pb_glossary]. In fact, [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] itself is the single most abundant [pb_glossary id=\"2687\"]mineral[\/pb_glossary] in the Earth\u2019s [pb_glossary id=\"2580\"]crust[\/pb_glossary]. There are two types of [pb_glossary id=\"1916\"]feldspar[\/pb_glossary], one containing potassium and abundant in [pb_glossary id=\"1954\"]felsic[\/pb_glossary] rocks of the [pb_glossary id=\"2575\"]continental crust[\/pb_glossary], and the other with sodium and calcium abundant in the [pb_glossary id=\"1956\"]mafic[\/pb_glossary] rocks of [pb_glossary id=\"2581\"]oceanic crust[\/pb_glossary].\u00a0 Together with [pb_glossary id=\"1915\"]quartz[\/pb_glossary], these [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are classified as framework [pb_glossary id=\"2709\"]silicates[\/pb_glossary]. They are built with a three-dimensional framework of [pb_glossary id=\"2710\"]silica tetrahedra[\/pb_glossary] in which all four corner oxygens are shared with adjacent tetrahedra. Within these frameworks in [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] are holes and spaces into which other ions like aluminum, potassium, sodium, and calcium can fit giving rise to a variety of [pb_glossary id=\"2687\"]mineral[\/pb_glossary] compositions and [pb_glossary id=\"2687\"]mineral[\/pb_glossary] names.\n\n[caption id=\"attachment_2781\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/min-crust-pie-chart.jpg\"><img class=\"size-medium wp-image-2781\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/min-crust-pie-chart-300x290-1.jpg\" alt=\"Feldspar is 51% of the chart.\" width=\"300\" height=\"290\"><\/a> Mineral abundance pie chart in Earth's crust by Callan Bentley.[\/caption]\n\n[pb_glossary id=\"1916\"]Feldspars[\/pb_glossary] are usually found in [pb_glossary id=\"2675\"]igneous[\/pb_glossary] rocks, such as [pb_glossary id=\"1962\"]granite[\/pb_glossary], [pb_glossary id=\"1958\"]rhyolite[\/pb_glossary], and [pb_glossary id=\"1961\"]basalt[\/pb_glossary] as well as [pb_glossary id=\"2914\"]metamorphic[\/pb_glossary] rocks and [pb_glossary id=\"3363\"]detrital[\/pb_glossary] sedimentary rocks. [pb_glossary id=\"3363\"]Detrital[\/pb_glossary] sedimentary rocks are [pb_glossary id=\"2831\"]composed[\/pb_glossary] of mechanically weathered rock particles, like sand and gravel. [pb_glossary id=\"1915\"]Quartz[\/pb_glossary] is especially abundant in [pb_glossary id=\"3363\"]detrital[\/pb_glossary] sedimentary rocks because it is very resistant to disintegration by [pb_glossary id=\"2676\"]weathering[\/pb_glossary]. While [pb_glossary id=\"1915\"]quartz[\/pb_glossary] is the most abundant [pb_glossary id=\"2687\"]mineral[\/pb_glossary] on the Earth's surface, due to its durability, the [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are the most abundant [pb_glossary id=\"2687\"]minerals[\/pb_glossary] in the Earth's [pb_glossary id=\"2580\"]crust[\/pb_glossary], comprising roughly 50% of the total [pb_glossary id=\"2687\"]minerals[\/pb_glossary] that make up the [pb_glossary id=\"2580\"]crust[\/pb_glossary].\n\n[caption id=\"attachment_2782\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.24_kspar280x210-1.jpg\"><img class=\"size-medium wp-image-2782\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.24_kspar280x210-1-300x200-1.jpg\" alt=\"A group of crystals of pink potassium feldspar\" width=\"300\" height=\"200\"><\/a> Pink orthoclase crystals[\/caption]\n\n&nbsp;\n\n[pb_glossary id=\"1915\"]Quartz[\/pb_glossary] is [pb_glossary id=\"2831\"]composed[\/pb_glossary] of pure silica, SiO<sub>2<\/sub>, with the tetrahedra arranged in a three dimensional framework. Impurities consisting of atoms within this framework give rise to many varieties of [pb_glossary id=\"1915\"]quartz[\/pb_glossary] among which are gemstones like amethyst, rose [pb_glossary id=\"1915\"]quartz[\/pb_glossary], and citrine.\u00a0 [pb_glossary id=\"1916\"]Feldspars[\/pb_glossary] are mostly silicon, oxygen, aluminum, potassium, sodium, and calcium. Orthoclase [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] (KAlSi<sub>3<\/sub>O<sub>8<\/sub>), also called potassium [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] or [pb_glossary id=\"1916\"]K-spar[\/pb_glossary], is made of silica, aluminum, and potassium. [pb_glossary id=\"1915\"]Quartz[\/pb_glossary] and orthoclase [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] are [pb_glossary id=\"1954\"]felsic[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. [pb_glossary id=\"1954\"]Felsic[\/pb_glossary] is the compositional term applied to [pb_glossary id=\"2575\"]continental[\/pb_glossary] [pb_glossary id=\"2675\"]igneous[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and rocks that contain an abundance of silica. Another [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] is [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] with the formula (Ca,Na)AlSi<sub>3<\/sub>O<sub>8<\/sub>, the [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] (Ca,Na) indicating a series of [pb_glossary id=\"2687\"]minerals[\/pb_glossary], one end of the series with calcium CaAl<sub>2<\/sub>Si<sub>2<\/sub>O<sub>8<\/sub>, called anorthite, and the other end with sodium NaAlSi<sub>3<\/sub>O<sub>8<\/sub>, called albite.\u00a0Note how the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] accommodates the substitution of Ca<sup>++<\/sup> and Na<sup>+<\/sup>. [pb_glossary id=\"2687\"]Minerals[\/pb_glossary] in this solid solution series have different [pb_glossary id=\"2687\"]mineral[\/pb_glossary] names.\n\n[caption id=\"attachment_2783\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/23-feldspar-structure.gif\"><img class=\"size-medium wp-image-2783\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/23-feldspar-structure-300x271-1.gif\" alt=\"Framework structure of feldspar with all corners of tetrahedra shared with adjacent tetrahedra; there are holes in the structure in which large anions like potassium and sodium\/calcium fit\" width=\"300\" height=\"271\"><\/a> Crystal structure of feldspar[\/caption]\n\nNote that aluminum, which has a similar ionic size to silicon, can substitute for silicon inside the tetrahedra (see figure). Because potassium ions are so much larger than sodium and calcium ions, which are very similar in size, the inability of the crystal lattice to accommodate both potassium and sodium\/calcium gives rise to the two families of [pb_glossary id=\"1916\"]feldspar[\/pb_glossary], orthoclase and [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] respectively.\u00a0Framework [pb_glossary id=\"2709\"]silicates[\/pb_glossary] are called tectosilicates and include the alkali metal-rich feldspathoids and zeolites.\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"19\"]\n\n[caption id=\"attachment_3752\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-175\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 3.3 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">3.4 Non-Silicate Minerals<\/span><\/h2>\n[caption id=\"attachment_2784\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite.jpg\"><img class=\"size-medium wp-image-2784\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Hanksite-300x200-1.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"300\" height=\"200\"><\/a> Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few minerals that is considered a carbonate and a sulfate[\/caption]\n\n&nbsp;\n\nThe crystal structure of non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] (see table) does not contain [pb_glossary id=\"2710\"]silica-oxygen tetrahedra[\/pb_glossary]. Many non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are economically important and provide [pb_glossary id=\"3345\"]metallic[\/pb_glossary] resources such as copper, lead, and iron. They also include valuable non-[pb_glossary id=\"3345\"]metallic[\/pb_glossary] products such as salt, construction materials, and fertilizer.\n<table>\n<tbody>\n<tr>\n<td><b>[pb_glossary id=\"2687\"]Mineral[\/pb_glossary] \u00a0Group<\/b><\/td>\n<td><b>Examples<\/b><\/td>\n<td><b>Formula<\/b><\/td>\n<td><b>Uses<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1924\"]Native[\/pb_glossary] [pb_glossary id=\"2700\"]elements[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">gold, silver, copper<\/span><\/td>\n<td><span style=\"font-weight: 400\">Au, Ag, Cu<\/span><\/td>\n<td><span style=\"font-weight: 400\">Jewelry, coins, industry<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1917\"]Carbonates[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1918\"]calcite[\/pb_glossary], dolomite <\/span><\/td>\n<td><span style=\"font-weight: 400\">CaCO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, CaMg(CO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><\/td>\n<td><span style=\"font-weight: 400\">Lime, Portland cement<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1919\"]Oxides[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">hematite, magnetite, [pb_glossary id=\"3357\"]bauxite[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">Fe<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">, a mixture of aluminum [pb_glossary id=\"1919\"]oxides[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"3325\"]Ores[\/pb_glossary] of iron &amp; aluminum, pigments <\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1920\"]Halides[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"2844\"]halite[\/pb_glossary], sylvite<\/span><\/td>\n<td><span style=\"font-weight: 400\">NaCl, KCl<\/span><\/td>\n<td><span style=\"font-weight: 400\">Table salt, fertilizer<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1921\"]Sulfides[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">galena, chalcopyrite, cinnabar<\/span><\/td>\n<td><span style=\"font-weight: 400\">PbS, CuFeS<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">, HgS<\/span><\/td>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"3325\"]Ores[\/pb_glossary] of lead, copper, mercury<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">Sulphates<\/span><\/td>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"2843\"]gypsum[\/pb_glossary], epsom salts<\/span><\/td>\n<td><span style=\"font-weight: 400\">CaSo<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b72H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O, MgSO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b77H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><\/td>\n<td><span style=\"font-weight: 400\">Sheetrock, therapeutic soak<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">[pb_glossary id=\"1923\"]Phosphates[\/pb_glossary]<\/span><\/td>\n<td><span style=\"font-weight: 400\">apatite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ca<\/span><sub><span style=\"font-weight: 400\">5<\/span><\/sub><span style=\"font-weight: 400\">(PO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">(F,Cl,OH) <\/span><\/td>\n<td><span style=\"font-weight: 400\">Fertilizer, teeth, bones<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<em><span style=\"font-weight: 400\">Common non-[pb_glossary id=\"2709\"]<em>silicate<\/em>[\/pb_glossary] [pb_glossary id=\"2687\"]<em>mineral<\/em>[\/pb_glossary] groups.<\/span><\/em>\n<h3><b>3.4.1 Carbonates<\/b><\/h3>\n[caption id=\"attachment_2785\" align=\"alignleft\" width=\"245\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"size-medium wp-image-2785\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"245\" height=\"300\"><\/a> Calcite crystal in shape of rhomb. Note the double-refracted word \u201ccalcite\u201d in the center of the figure due to birefringence.[\/caption]\n\n[caption id=\"attachment_2786\" align=\"alignright\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.29_Limestone_etched_section_KopeFm_new.jpg\"><img class=\"wp-image-2786\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.29_Limestone_etched_section_KopeFm_new-281x300-1.jpg\" alt=\"Piece of limestone rock full of small fossils\" width=\"200\" height=\"214\"><\/a> Limestone with small fossils[\/caption]\n\n[pb_glossary id=\"1918\"]Calcite[\/pb_glossary]\u00a0(CaCO<sub>3<\/sub>) and dolomite (CaMg(CO<sub>3<\/sub>)<sub>2<\/sub>) are the two most frequently occurring [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary], and usually occur in sedimentary rocks, such as [pb_glossary id=\"2851\"]limestone[\/pb_glossary] and dolostone rocks, respectively. Some [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] rocks, such [pb_glossary id=\"1918\"]calcite[\/pb_glossary] and dolomite, are formed via evaporation and [pb_glossary id=\"2707\"]precipitation[\/pb_glossary]. However, most [pb_glossary id=\"1917\"]carbonate[\/pb_glossary]-rich rocks, such as [pb_glossary id=\"2851\"]limestone[\/pb_glossary], are created by the [pb_glossary id=\"2682\"]lithification[\/pb_glossary] of fossilized [pb_glossary id=\"2883\"]marine[\/pb_glossary] organisms. These organisms, including those we can see and many microscopic organisms, have shells or exoskeletons consisting of calcium [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] (CaCO<sub>3<\/sub>). When these organisms die, their remains accumulate on the floor of the water body in which they live and the soft body parts decompose and [pb_glossary id=\"2815\"]dissolve[\/pb_glossary] away. The calcium [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] hard parts become included in the [pb_glossary id=\"2678\"]sediments[\/pb_glossary], eventually becoming the [pb_glossary id=\"2683\"]sedimentary rock[\/pb_glossary] called [pb_glossary id=\"2851\"]limestone[\/pb_glossary]. While [pb_glossary id=\"2851\"]limestone[\/pb_glossary] may contain large, easy to see [pb_glossary id=\"2176\"]fossils[\/pb_glossary], most [pb_glossary id=\"2851\"]limestones[\/pb_glossary] contain the remains of microscopic creatures and thus originate from biological processes.\n\n[caption id=\"attachment_2787\" align=\"alignleft\" width=\"282\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bifringence.jpg\"><img class=\"size-medium wp-image-2787\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Bifringence-282x300-1.jpg\" alt=\"Calcite crystal polarize light into two waves that vibrate at right angles to each other and pass through the crystal in different paths.\" width=\"282\" height=\"300\"><\/a> Bifringence in calcite crystals[\/caption]\n\n[pb_glossary id=\"1918\"]Calcite[\/pb_glossary] crystals show an interesting property called <strong>birefringence<\/strong>, meaning they polarize light into two wave components vibrating at right angles to each other. As the two light waves pass through the crystal, they travel at different velocities and are separated by [pb_glossary id=\"3091\"]refraction[\/pb_glossary] into two different travel paths. In other words, the crystal produces a double image of objects viewed through it. Because they polarize light, [pb_glossary id=\"1918\"]calcite[\/pb_glossary] crystals are used in special petrographic microscopes for studying [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and rocks.\n\nMany non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are referred to as salts. The term <strong>salts<\/strong> used here refers to compounds made by replacing the hydrogen in natural acids. The most abundant natural acid is [pb_glossary id=\"2813\"]carbonic acid[\/pb_glossary] that forms by the [pb_glossary id=\"2705\"]solution[\/pb_glossary] of carbon dioxide in water. [pb_glossary id=\"1917\"]Carbonate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are salts built around the [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] [pb_glossary id=\"3371\"]ion[\/pb_glossary] (CO3<sup>-2<\/sup>) where calcium and\/or magnesium replace the hydrogen in [pb_glossary id=\"2813\"]carbonic acid[\/pb_glossary] (H<sub>2<\/sub>CO<sub>3<\/sub>). [pb_glossary id=\"1918\"]Calcite[\/pb_glossary] and a closely related [pb_glossary id=\"3362\"]polymorph[\/pb_glossary] aragonite are secreted by organisms to form shells and physical structures like corals. Many such creatures draw both calcium and [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] from [pb_glossary id=\"2815\"]dissolved[\/pb_glossary] bicarbonate ions (HCO<sub>3<\/sub><sup>-<\/sup>) in ocean water. As seen in the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] identification section below, [pb_glossary id=\"1918\"]calcite[\/pb_glossary] is easily [pb_glossary id=\"2815\"]dissolved[\/pb_glossary] in acid and thus effervesces in dilute hydrochloric acid (HCl). Small dropper bottles of dilute hydrochloric acid are often carried by geologists in the field as well as used in [pb_glossary id=\"2687\"]mineral[\/pb_glossary] identification labs.\n\nOther salts include [pb_glossary id=\"2844\"]halite[\/pb_glossary] (NaCl) in which sodium replaces the hydrogen in hydrochloric acid and [pb_glossary id=\"2843\"]gypsum[\/pb_glossary] (Ca[SO<sub>4<\/sub>] \u2022 2 H<sub>2<\/sub>O) in which calcium replaces the hydrogen in sulfuric acid. Note that some water molecules are also included in the [pb_glossary id=\"2843\"]gypsum[\/pb_glossary] crystal. Salts are often formed by evaporation and are called [pb_glossary id=\"2842\"]evaporite[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary].\n\n[caption id=\"attachment_2788\" align=\"alignleft\" width=\"425\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.30_Crystal_structure_of_Calcite.png\"><img class=\"wp-image-2788\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.30_Crystal_structure_of_Calcite.png\" alt=\"Crystal structure of calcite showing the carbonate units of carbon surrounded by three oxygen ions and bonded to calcium ions.\" width=\"425\" height=\"520\"><\/a> Crystal structure of calcite[\/caption]\n\nThe figure shows the crystal structure of [pb_glossary id=\"1918\"]calcite[\/pb_glossary] (CaCO<sub>3<\/sub>). Like silicon, carbon has four valence electrons. The [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] unit consists of carbon atoms (tiny white dots) covalently [pb_glossary id=\"2703\"]bonded[\/pb_glossary] to three oxygen atoms (red), one oxygen sharing two valence electrons with the carbon and the other two sharing one valence electron each with the carbon, thus creating triangular units with a charge of -2. The negatively charged [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] unit forms an ionic [pb_glossary id=\"2703\"]bond[\/pb_glossary] with the Ca [pb_glossary id=\"3371\"]ion[\/pb_glossary] (blue), which as a charge of +2.\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><b>3.4.2 Oxides, Halides, and Sulfides<\/b><\/h3>\n[caption id=\"attachment_2789\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"size-medium wp-image-2789\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"300\" height=\"256\"><\/a> Limonite, a hydrated oxide of iron[\/caption]\n\nAfter [pb_glossary id=\"1917\"]carbonates[\/pb_glossary], the next most common non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are the [pb_glossary id=\"1919\"]oxides[\/pb_glossary], [pb_glossary id=\"1920\"]halides[\/pb_glossary], and [pb_glossary id=\"1921\"]sulfides[\/pb_glossary].\n\n[pb_glossary id=\"1919\"]Oxides[\/pb_glossary] consist of metal ions covalently [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with oxygen. The most familiar [pb_glossary id=\"1919\"]oxide[\/pb_glossary] is rust, which is a combination of iron [pb_glossary id=\"1919\"]oxides[\/pb_glossary] (Fe<sub>2<\/sub>O<sub>3<\/sub>) and hydrated [pb_glossary id=\"1919\"]oxides[\/pb_glossary]. Hydrated [pb_glossary id=\"1919\"]oxides[\/pb_glossary] form when iron is exposed to oxygen and water. Iron [pb_glossary id=\"1919\"]oxides[\/pb_glossary] are important for producing [pb_glossary id=\"3345\"]metallic[\/pb_glossary] iron. When iron [pb_glossary id=\"1919\"]oxide[\/pb_glossary] or [pb_glossary id=\"3325\"]ore[\/pb_glossary] is smelted, it produces carbon dioxide (CO<sub>2<\/sub>) and [pb_glossary id=\"3345\"]metallic[\/pb_glossary] iron.\n\nThe red color in rocks is usually due to the presence of iron [pb_glossary id=\"1919\"]oxides[\/pb_glossary]. For example, the red [pb_glossary id=\"2834\"]sandstone[\/pb_glossary] cliffs in Zion National Park and throughout Southern Utah consist of white or colorless grains of [pb_glossary id=\"1915\"]quartz[\/pb_glossary] coated with iron [pb_glossary id=\"1919\"]oxide[\/pb_glossary] which serve as cementing agents holding the grains together.\n\n[caption id=\"attachment_2790\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503.jpg\"><img class=\"wp-image-2790 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503-300x269-1.jpg\" alt=\"A red form of hematite called oolitic showing a mass of small round nodules\" width=\"300\" height=\"269\"><\/a> Oolitic hematite[\/caption]\n\nOther iron [pb_glossary id=\"1919\"]oxides[\/pb_glossary] include limonite, magnetite, and hematite. Hematite occurs in many different crystal forms. The [pb_glossary id=\"1933\"]massive[\/pb_glossary] form shows no external structure. Botryoidal hematite shows large concentric blobs. Specular hematite looks like a mass of shiny [pb_glossary id=\"3345\"]metallic[\/pb_glossary] crystals. Oolitic hematite looks like a mass of dull red fish eggs. These different forms of hematite are [pb_glossary id=\"2940\"]polymorphs[\/pb_glossary] and all have the same formula, Fe<sub>2<\/sub>O<sub>3<\/sub>.\n\nOther common [pb_glossary id=\"1919\"]oxide[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] include:\n<ul>\n \t<li>ice (H<sub>2<\/sub>O), an [pb_glossary id=\"1919\"]oxide[\/pb_glossary] of hydrogen<\/li>\n \t<li>[pb_glossary id=\"3357\"]bauxite[\/pb_glossary] (Al<sub>2<\/sub>H<sub>2<\/sub>O<sub>4<\/sub>), hydrated [pb_glossary id=\"1919\"]oxides[\/pb_glossary] of aluminum, an [pb_glossary id=\"3325\"]ore[\/pb_glossary] for producing [pb_glossary id=\"3345\"]metallic[\/pb_glossary] aluminum<\/li>\n \t<li>corundum (Al<sub>2<\/sub>O<sub>3<\/sub>), which includes ruby and sapphire gemstones.<\/li>\n<\/ul>\n&nbsp;\n\n[caption id=\"attachment_2791\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.34_Halite-249324-1.jpg\"><img class=\"size-medium wp-image-2791\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.34_Halite-249324-1-300x225-1.jpg\" alt=\"Crystals of halite showing cubic crystal habit\" width=\"300\" height=\"225\"><\/a> Halite crystal showing cubic habit[\/caption]\n\nThe <strong>[pb_glossary id=\"1920\"]halides[\/pb_glossary]<\/strong> consist of halogens in column VII, usually fluorine or chlorine, ionically [pb_glossary id=\"2703\"]bonded[\/pb_glossary] with sodium or other [pb_glossary id=\"2702\"]cations[\/pb_glossary]. These include [pb_glossary id=\"2844\"]halite[\/pb_glossary] or sodium chloride (NaCl), common table salt; sylvite or potassium chloride (KCl); and fluorite or calcium fluoride (CaF<sub>2<\/sub>).\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n[caption id=\"attachment_2792\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level.jpg\"><img class=\"size-medium wp-image-2792\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level-300x220-1.jpg\" alt=\"Photo of salt crust at the Bonneville Salt Flats in Utah with mountains in the background.\" width=\"300\" height=\"220\"><\/a> Salt crystals at the Bonneville Salt Flats[\/caption]\n\n[caption id=\"attachment_2793\" align=\"alignright\" width=\"244\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a> Fluorite. B shows fluorescence of fluorite under UV light[\/caption]\n\n[pb_glossary id=\"1920\"]Halide[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] usually form from the evaporation of sea water or other isolated bodies of water. A well-known example of [pb_glossary id=\"1920\"]halide[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] deposits created by evaporation is the Bonneville Salt Flats, located west of the Great Salt Lake in Utah (see figure).\n\n&nbsp;\n\nMany important metal [pb_glossary id=\"3325\"]ores[\/pb_glossary] are <b>[pb_glossary id=\"1921\"]sulfides[\/pb_glossary], <\/b><span style=\"font-weight: 400\">in which metals are [pb_glossary id=\"2703\"]bonded[\/pb_glossary] to sulfur.\u00a0<\/span><span style=\"font-weight: 400\">Significant examples include: \u00a0<\/span>galena<span style=\"font-weight: 400\"> (lead [pb_glossary id=\"1921\"]sulfide[\/pb_glossary]), <\/span>sphalerite<span style=\"font-weight: 400\"> (zinc [pb_glossary id=\"1921\"]sulfide[\/pb_glossary]),<\/span> pyrite\n\n[caption id=\"attachment_2794\" align=\"alignright\" width=\"175\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.37_pyrite1.jpg\"><img class=\"wp-image-2794\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.37_pyrite1-283x300-1.jpg\" alt=\"Cubic crystals of iron pyrite, called &quot;fools gold&quot;\" width=\"175\" height=\"185\"><\/a> Cubic crystals of pyrite[\/caption]\n\n<span style=\"font-weight: 400\">(<\/span><span style=\"font-weight: 400\">iron<\/span><span style=\"font-weight: 400\">\u00a0[pb_glossary id=\"1921\"]sulfide[\/pb_glossary], sometimes called \u201cfool's gold\u201d), and <\/span>chalcopyrite <span style=\"font-weight: 400\">(iron-copper [pb_glossary id=\"1921\"]sulfide[\/pb_glossary]).<\/span><span style=\"font-weight: 400\">\u00a0[pb_glossary id=\"1921\"]Sulfides[\/pb_glossary] are well known for being important [pb_glossary id=\"3325\"]ore[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. For example, galena is the main source of lead, sphalerite is the main source of zinc, and chalcopyrite is the main copper [pb_glossary id=\"3325\"]ore[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"3324\"]mined[\/pb_glossary] in porphyry deposits like the Bingham [pb_glossary id=\"3324\"]mine[\/pb_glossary] (see <a href=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/chapter\/16-energy-and-mineral-resources\/\">chapter 16<\/a>). The largest sources of nickel, antimony, molybdenum, arsenic, and mercury are also [pb_glossary id=\"1921\"]sulfides[\/pb_glossary].<\/span>\n<h3><b>3.4.3 Sulfates<\/b><\/h3>\n[caption id=\"attachment_2795\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.39_SeleniteGypsumUSGOV.jpg\"><img class=\"size-medium wp-image-2795\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.39_SeleniteGypsumUSGOV-300x284-1.jpg\" alt=\"A clear crystal of gypsum\" width=\"300\" height=\"284\"><\/a> Gypsum crystal[\/caption]\n\n[pb_glossary id=\"1922\"]Sulfate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] contain a metal [pb_glossary id=\"3371\"]ion[\/pb_glossary], such as calcium, [pb_glossary id=\"2703\"]bonded[\/pb_glossary] to a [pb_glossary id=\"1922\"]sulfate[\/pb_glossary] [pb_glossary id=\"3371\"]ion[\/pb_glossary]. The [pb_glossary id=\"1922\"]sulfate[\/pb_glossary] [pb_glossary id=\"3371\"]ion[\/pb_glossary] is a combination of sulfur and oxygen (SO<sub>4<sup>-<\/sup><\/sub><sup>2<\/sup>). The [pb_glossary id=\"1922\"]sulfate[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] [pb_glossary id=\"2843\"]gypsum[\/pb_glossary] (CaSO<sub>4<\/sub>\u14272H<sub>2<\/sub>O) is used in construction materials such as plaster and drywall. [pb_glossary id=\"2843\"]Gypsum[\/pb_glossary] is often formed from evaporating water and usually contains water molecules in its crystalline structure. The \u14272H<sub>2<\/sub>O in the formula indicates the water molecules are whole H<sub>2<\/sub>O. This is different from [pb_glossary id=\"2687\"]minerals[\/pb_glossary] like [pb_glossary id=\"2713\"]amphibole[\/pb_glossary], which contain a hydroxide [pb_glossary id=\"3371\"]ion[\/pb_glossary] (OH<sup>-<\/sup>) that is derived from water, but is missing a hydrogen ion (H<sup>+<\/sup>). The calcium [pb_glossary id=\"1922\"]sulfate[\/pb_glossary] without water is a different [pb_glossary id=\"2687\"]mineral[\/pb_glossary] than [pb_glossary id=\"2843\"]gypsum[\/pb_glossary] called anhydrite (CaSO<sub>4<\/sub>).\n<h3><b>3.4.4 Phosphates<\/b><\/h3>\n[caption id=\"attachment_2796\" align=\"alignright\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.40_Apatite_Canada.jpg\"><img class=\"wp-image-2796\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.40_Apatite_Canada-236x300-1.jpg\" alt=\"A crystal of apatite\" width=\"150\" height=\"191\"><\/a> Apatite crystal[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1923\"]Phosphate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] have a tetrahedral [pb_glossary id=\"1923\"]phosphate[\/pb_glossary] unit (PO<sub>4<\/sub><sup>-3<\/sup>) combined with various [pb_glossary id=\"2704\"]anions[\/pb_glossary] and [pb_glossary id=\"2702\"]cations[\/pb_glossary]. In some cases arsenic or vanadium can substitute for phosphorus. [pb_glossary id=\"1923\"]Phosphates[\/pb_glossary] are an important ingredient of fertilizers as well as detergents, paint, and other products. The best known [pb_glossary id=\"1923\"]phosphate[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] is apatite, Ca<sub>5<\/sub>(PO<sub>4<\/sub>)<sub>3<\/sub>(F,Cl,OH), variations of which are found in teeth and bones. The gemstone turquoise [CuAl<sub>6<\/sub>(PO<sub>4<\/sub>)<sub>4<\/sub>(OH)<sub>8<\/sub>\u00b74H2O ] is a copper-rich [pb_glossary id=\"1923\"]phosphate[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] that, like [pb_glossary id=\"2843\"]gypsum[\/pb_glossary], contains water molecules.<\/span>\n<h3><b>3.4.5 Native Element Minerals<\/b><\/h3>\n[caption id=\"attachment_2798\" align=\"alignleft\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.43_Sulfer_Fumarola_Vulcano.jpg\"><img class=\"wp-image-2798\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.43_Sulfer_Fumarola_Vulcano-300x225-1.jpg\" alt=\"Native sulfur deposited around the vent of a volcanic fumarole\" width=\"200\" height=\"150\"><\/a> Native sulfur deposited around a volcanic fumarole[\/caption]\n\n[caption id=\"attachment_2797\" align=\"alignright\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.41_Native_Copper-1.jpg\"><img class=\"wp-image-2797\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.41_Native_Copper-1-300x284-1.jpg\" alt=\"Metallic native copper\" width=\"200\" height=\"189\"><\/a> Native copper[\/caption]\n\n[pb_glossary id=\"1924\"]Native element minerals[\/pb_glossary], usually metals, occur in nature in a pure or nearly pure state. Gold is an example of a [pb_glossary id=\"1924\"]native[\/pb_glossary] [pb_glossary id=\"2700\"]element[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary]; it is not very reactive and rarely [pb_glossary id=\"2703\"]bonds[\/pb_glossary] with other [pb_glossary id=\"2700\"]elements[\/pb_glossary] so it is usually found in an isolated or pure state. The non-[pb_glossary id=\"3345\"]metallic[\/pb_glossary] and poorly-reactive [pb_glossary id=\"2687\"]mineral[\/pb_glossary] carbon is often found as a [pb_glossary id=\"1924\"]native[\/pb_glossary] [pb_glossary id=\"2700\"]element[\/pb_glossary], such as graphite and diamonds. Mildly reactive metals like silver, copper, platinum, mercury, and sulfur sometimes occur as [pb_glossary id=\"1924\"]native element minerals[\/pb_glossary]. Reactive metals such as iron, lead, and aluminum almost always [pb_glossary id=\"2703\"]bond[\/pb_glossary] to other [pb_glossary id=\"2700\"]elements[\/pb_glossary] and are rarely found in a [pb_glossary id=\"1924\"]native[\/pb_glossary] state.\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"20\"]\n\n[caption id=\"attachment_3751\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-191\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 3.4 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">3.5 Identifying Minerals<\/span><\/h2>\n[caption id=\"attachment_2799\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Curiosity_Mars_Rover_Finds_Mineral_Match.jpg\"><img class=\"size-medium wp-image-2799\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Curiosity_Mars_Rover_Finds_Mineral_Match-300x268-1.jpg\" alt=\"The red rocks have a small hole drilled\" width=\"300\" height=\"268\"><\/a> The rover Curiosity drilled a hole in this rock from Mars, and confirmed the mineral Hematite, as mapped from satellites.[\/caption]\n\nGeologists identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] by their physical properties. In the field, where geologists may have limited access to advanced technology and powerful machines, they can still identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] by testing several physical properties: [pb_glossary id=\"1925\"]luster[\/pb_glossary] and color, [pb_glossary id=\"1926\"]streak[\/pb_glossary], [pb_glossary id=\"1927\"]hardness[\/pb_glossary], [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary], cleavage and [pb_glossary id=\"1934\"]fracture[\/pb_glossary], and some special properties. Only a few common [pb_glossary id=\"2687\"]minerals[\/pb_glossary] make up the majority of Earth's rocks and are usually seen as small grains in rocks. Of the several properties used for identifying [pb_glossary id=\"2687\"]minerals[\/pb_glossary], it is good to consider which will be most useful for identifying them in small grains surrounded by other [pb_glossary id=\"2687\"]minerals[\/pb_glossary].\n<h3><b>3.5.1 Luster and Color<\/b><\/h3>\n[caption id=\"attachment_2800\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Molly_Hill_molybdenite.jpg\"><img class=\"size-medium wp-image-2800\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Molly_Hill_molybdenite-300x225-1.jpg\" alt=\"The crystal looks like metal.\" width=\"300\" height=\"225\"><\/a> 15 mm metallic hexagonal molybdenite crystal from Quebec.[\/caption]\n\n&nbsp;\n\nThe first thing to notice about a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] is its surface appearance, specifically [pb_glossary id=\"1925\"]luster[\/pb_glossary] and color. [pb_glossary id=\"1925\"]Luster[\/pb_glossary] describes how the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] looks. [pb_glossary id=\"3345\"]Metallic[\/pb_glossary] [pb_glossary id=\"1925\"]luster[\/pb_glossary] looks like a shiny metal such as chrome, steel, silver, or gold. Submetallic [pb_glossary id=\"1925\"]luster[\/pb_glossary] has a duller appearance. Pewter, for example, shows submetallic [pb_glossary id=\"1925\"]luster[\/pb_glossary].\n\n[caption id=\"attachment_2801\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pewter-plate.jpg\"><img class=\"size-medium wp-image-2801\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Pewter-plate-300x280-1.jpg\" alt=\"Antique pewter plate showing a more dull submetallic luster\" width=\"300\" height=\"280\"><\/a> Submetallic luster shown on an antique pewter plate.[\/caption]\n\n&nbsp;\n\n&nbsp;\n\n[pb_glossary id=\"3346\"]Nonmetallic[\/pb_glossary] [pb_glossary id=\"1925\"]luster[\/pb_glossary] doesn\u2019t look like a metal and may be described as vitreous (glassy), earthy, silky, pearly, and other surface qualities. [pb_glossary id=\"3346\"]Nonmetallic[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] may be shiny, although their vitreous shine is different from [pb_glossary id=\"3345\"]metallic[\/pb_glossary] [pb_glossary id=\"1925\"]luster[\/pb_glossary]. See the table for descriptions and examples of [pb_glossary id=\"3346\"]nonmetallic[\/pb_glossary] [pb_glossary id=\"1925\"]luster[\/pb_glossary].\n<table style=\"width: 680px;height: 859px\">\n<tbody>\n<tr style=\"height: 32.625px\">\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">[pb_glossary id=\"1925\"]Luster[\/pb_glossary]<\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Image<\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Description<\/span><\/th>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Vitreous\/glassy<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_3669\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.23_-Quartz_Bresil.jpg\"><img class=\"size-thumbnail wp-image-195\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.23_-Quartz_Bresil-150x150.jpg\" alt=\"A mass of quartz crystals showing typical six sided habit with points\" width=\"150\" height=\"150\"><\/a> Quartz crystals[\/caption]<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Surface is shiny like glass<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Earthy\/dull<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2802\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.47_earthy_luster_KaolinUSGOV-1.jpg\"><img class=\"size-thumbnail wp-image-2802\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.47_earthy_luster_KaolinUSGOV-1-150x150-1.jpg\" alt=\"Specimen of kaolin, a clay oineral, showing dull or earthy luster\" width=\"150\" height=\"150\"><\/a> Kaolin specimen showing dull or earthy luster[\/caption]<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Dull, like dried mud or clay<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Silky<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2803\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.48_silky_luster_Selenite_Gips_Marienglas-1.jpg\"><img class=\"wp-image-2803\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.48_silky_luster_Selenite_Gips_Marienglas-1-300x230-1.jpg\" alt=\"Specimen showing silky luster\" width=\"150\" height=\"115\"><\/a> Specimen showing silky luster[\/caption]<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Soft shine like silk fabric<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Pearly<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2804\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.49_pearly_luster_Mineral_Mica_GDFL006.jpg\"><img class=\"wp-image-2804\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.49_pearly_luster_Mineral_Mica_GDFL006-300x218-1.jpg\" alt=\"Specimen showing pearly luster like the inside of a clam shell\" width=\"150\" height=\"109\"><\/a> Specimen showing pearly luster[\/caption]<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Like the inside of a clam shell or mother-of-pearl<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Submetallic<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2805\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.44_submetallic_Sphalerite4.jpg\"><img class=\"wp-image-2805\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.44_submetallic_Sphalerite4-300x277-1.jpg\" alt=\"Photo of mineral exhibiting submetallic luster\" width=\"150\" height=\"138\"><\/a> Submetallic luster on sphalerite[\/caption]<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Has the appearance of dull metal,\u00a0like pewter. These [pb_glossary id=\"2687\"]minerals[\/pb_glossary] would usually still be considered [pb_glossary id=\"3345\"]metallic[\/pb_glossary]. Submetallic appearance can occur in [pb_glossary id=\"3345\"]metallic[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] because of [pb_glossary id=\"2676\"]weathering[\/pb_glossary].<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n[caption id=\"attachment_2806\" align=\"alignleft\" width=\"245\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Azurite_in_siltstone_Malbunka_mine_NT.jpg\"><img class=\"size-medium wp-image-2806\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Azurite_in_siltstone_Malbunka_mine_NT-245x300-1.jpg\" alt=\"There are two dark blue disks on white siltstone.\" width=\"245\" height=\"300\"><\/a> Azurite is ALWAYS a dark blue color, and has been used for centuries for blue pigment.[\/caption]\n\nSurface color may be helpful in identifying [pb_glossary id=\"2687\"]minerals[\/pb_glossary], although it can be quite variable within the same [pb_glossary id=\"2687\"]mineral[\/pb_glossary] family. [pb_glossary id=\"2687\"]Mineral[\/pb_glossary] colors are affected by the main [pb_glossary id=\"2700\"]elements[\/pb_glossary] as well as impurities in the crystals. These impurities may be rare [pb_glossary id=\"2700\"]elements[\/pb_glossary]\u2014like manganese, titanium, chromium, or lithium\u2014even other molecules that are not normally part of the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] formula. For example, the incorporation of water molecules gives [pb_glossary id=\"1915\"]quartz[\/pb_glossary], which is normally clear, a milky color.\n\nSome [pb_glossary id=\"2687\"]minerals[\/pb_glossary] predominantly show a single color. Malachite and azurite are green and blue, respectively, because of their copper content. Other [pb_glossary id=\"2687\"]minerals[\/pb_glossary] have a predictable range of colors due to elemental substitutions, usually via a [pb_glossary id=\"2708\"]solid solution[\/pb_glossary]. [pb_glossary id=\"1916\"]Feldspars[\/pb_glossary], the most abundant [pb_glossary id=\"2687\"]minerals[\/pb_glossary] in the earth\u2019s [pb_glossary id=\"2580\"]crust[\/pb_glossary], are complex, have [pb_glossary id=\"2708\"]solid solution[\/pb_glossary] series, and present several colors including pink, white, green, gray and others. Other [pb_glossary id=\"2687\"]minerals[\/pb_glossary] also come in several colors, influenced by trace amounts of several [pb_glossary id=\"2700\"]elements[\/pb_glossary]. The same [pb_glossary id=\"2700\"]element[\/pb_glossary] may show up as different colors, in different [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. With notable exceptions, color is usually not a definitive property of [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. For identifying many [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. a more reliable indicator is [pb_glossary id=\"1926\"]streak[\/pb_glossary], which is the color of the powdered [pb_glossary id=\"2687\"]mineral[\/pb_glossary].\n<h3><b>3.5.2 Streak<\/b><\/h3>\n[caption id=\"attachment_2807\" align=\"alignright\" width=\"450\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-scaled.jpg\"><img class=\"wp-image-2807\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-300x227-1.jpg\" alt=\"Pyrite showing a black streak on a white streak plate and rhodochrosite with a white streak on a black streak plate\" width=\"450\" height=\"341\"><\/a> Different minerals may have different streaks[\/caption]\n\n[pb_glossary id=\"1926\"]Streak[\/pb_glossary] examines the color of a powdered [pb_glossary id=\"2687\"]mineral[\/pb_glossary], and can be seen when a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] sample is scratched or scraped on an unglazed porcelain [pb_glossary id=\"1926\"]streak[\/pb_glossary] [pb_glossary id=\"2591\"]plate[\/pb_glossary]. A paper page in a field notebook may also be used for the [pb_glossary id=\"1926\"]streak[\/pb_glossary] of some [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. [pb_glossary id=\"2687\"]Minerals[\/pb_glossary] that are harder than the [pb_glossary id=\"1926\"]streak[\/pb_glossary] [pb_glossary id=\"2591\"]plate[\/pb_glossary] will not show [pb_glossary id=\"1926\"]streak[\/pb_glossary], but will scratch the porcelain. For these [pb_glossary id=\"2687\"]minerals[\/pb_glossary], a [pb_glossary id=\"1926\"]streak[\/pb_glossary] test can be obtained by powdering the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] with a hammer and smearing the powder across a [pb_glossary id=\"1926\"]streak[\/pb_glossary] [pb_glossary id=\"2591\"]plate[\/pb_glossary] or notebook paper.\n\nWhile [pb_glossary id=\"2687\"]mineral[\/pb_glossary] surface colors and appearances may vary, their [pb_glossary id=\"1926\"]streak[\/pb_glossary] colors can be diagnostically useful. An example of this property is seen in the iron-[pb_glossary id=\"1919\"]oxide[\/pb_glossary] [pb_glossary id=\"2687\"]mineral[\/pb_glossary] hematite. Hematite occurs in a variety of forms, colors and lusters, from shiny [pb_glossary id=\"3345\"]metallic[\/pb_glossary] silver to earthy red-brown, and different physical appearances. A hematite [pb_glossary id=\"1926\"]streak[\/pb_glossary] is consistently reddish brown, no matter what the original specimen looks like. Iron [pb_glossary id=\"1921\"]sulfide[\/pb_glossary] or pyrite, is a brassy [pb_glossary id=\"3345\"]metallic[\/pb_glossary] yellow. Commonly named fool\u2019s gold, pyrite has a characteristic black to greenish-black [pb_glossary id=\"1926\"]streak[\/pb_glossary].\n<h3><b>3.5.3 Hardness<\/b><\/h3>\n[caption id=\"attachment_2808\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.51_Mohs_Scale2.jpg\"><img class=\"size-large wp-image-2808\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.51_Mohs_Scale2-1024x714-1.jpg\" alt=\"Chart of Mohs Hardness Scale with minerals arranged in hardness from 1 to 10, also showing common items that correlate with the scale.\" width=\"1024\" height=\"714\"><\/a> Mohs Hardness Scale[\/caption]\n\n[pb_glossary id=\"1927\"]Hardness[\/pb_glossary] measures the ability of a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] to scratch other substances. The Mohs [pb_glossary id=\"1927\"]Hardness[\/pb_glossary] Scale gives a number showing the relative scratch-resistance of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] when compared to a standardized set of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] of increasing hardness. The Mohs scale was developed by German geologist Fredrick Mohs in the early 20th century, although the idea of identifying [pb_glossary id=\"2687\"]minerals[\/pb_glossary] by [pb_glossary id=\"1927\"]hardness[\/pb_glossary] goes back thousands of years. Mohs [pb_glossary id=\"1927\"]hardness[\/pb_glossary] values are determined by the strength of a [pb_glossary id=\"2687\"]mineral[\/pb_glossary]\u2019s atomic [pb_glossary id=\"2703\"]bonds[\/pb_glossary].\n\nThe figure shows the [pb_glossary id=\"2687\"]minerals[\/pb_glossary] associated with specific [pb_glossary id=\"1927\"]hardness[\/pb_glossary] values, together with some common items readily available for use in field testing and [pb_glossary id=\"2687\"]mineral[\/pb_glossary] identification. The [pb_glossary id=\"1927\"]hardness[\/pb_glossary] values run from 1 to 10, with 10 being the hardest; however, the scale is not linear. Diamond defines a [pb_glossary id=\"1927\"]hardness[\/pb_glossary] of 10 and is actually about four times harder than corundum, which is 9. A steel pocketknife blade, which has a [pb_glossary id=\"1927\"]hardness[\/pb_glossary] value of 5.5, separates between hard and soft [pb_glossary id=\"2687\"]minerals[\/pb_glossary] on many [pb_glossary id=\"2687\"]mineral[\/pb_glossary] identification keys.\n<h3><b>3.5.4 Crystal Habit<\/b><\/h3>\n[pb_glossary id=\"2687\"]Minerals[\/pb_glossary] can be identified by <strong>[pb_glossary id=\"1928\"]crystal habit[\/pb_glossary]<\/strong>, how their crystals grow and appear in rocks. Crystal shapes are determined by the arrangement of the atoms within the crystal structure. For example, a cubic arrangement of atoms gives rise to a cubic-shaped [pb_glossary id=\"2687\"]mineral[\/pb_glossary] crystal. [pb_glossary id=\"1928\"]Crystal habit[\/pb_glossary] refers to typically observed shapes and characteristics; however, they can be affected by other [pb_glossary id=\"2687\"]minerals[\/pb_glossary] crystallizing in the same rock. When [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are constrained so they do not develop their typical [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary], they are called <strong>[pb_glossary id=\"1929\"]anhedral[\/pb_glossary]<\/strong>. <strong>[pb_glossary id=\"1930\"]Subhedral[\/pb_glossary]<\/strong> crystals are partially formed shapes. For some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] characteristic [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary] is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. [pb_glossary id=\"2687\"]Minerals[\/pb_glossary] grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces. A <strong>[pb_glossary id=\"1931\"]euhedral[\/pb_glossary]<\/strong> crystal has a perfectly formed, unconstrained shape. Some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] crystallize in such tiny crystals, they do not show a specific [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary] to the naked eye. Other [pb_glossary id=\"2687\"]minerals[\/pb_glossary], like pyrite, can have an array of different crystal habits, including cubic, dodecahedral, octahedral, and [pb_glossary id=\"1933\"]massive[\/pb_glossary]. The table lists typical crystal habits of various [pb_glossary id=\"2687\"]minerals[\/pb_glossary].\n<table style=\"width: 687px;height: 3774px\">\n<tbody>\n<tr>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">[pb_glossary id=\"1928\"]Habit[\/pb_glossary]<\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Image<\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Examples<\/span><\/strong><\/th>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Bladed<\/strong>\n\nlong and flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2809\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Kyanite_crystals.jpg\"><img class=\"wp-image-2809\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Kyanite_crystals-300x225-1.jpg\" alt=\"The crystals are long and rectangular\" width=\"150\" height=\"113\"><\/a> Bladed kyanite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">kyanite,\u00a0[pb_glossary id=\"2713\"]amphibole[\/pb_glossary], [pb_glossary id=\"2843\"]gypsum[\/pb_glossary]<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Botryoidal\/mammillary<\/strong>\n\nblobby, circular crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2810\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Malachite_Kolwezi_Katanga_Congo.jpg\"><img class=\"wp-image-2810\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Malachite_Kolwezi_Katanga_Congo-300x174-1.jpg\" alt=\"The mineral is bulbous\" width=\"150\" height=\"87\"><\/a> Malachite from the Congo[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">hematite, malachite, smithsonite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Coating\/[pb_glossary id=\"2860\"]laminae[\/pb_glossary]\/druse<\/strong>\n\ncrystals that are small and coat surfaces<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2811\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ametyst-geode.jpg\"><img class=\"wp-image-2811\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ametyst-geode-300x200-1.jpg\" alt=\"The rock is hollowed and filled with purple minerals\" width=\"150\" height=\"100\"><\/a> Quartz (var. amethyst) geode[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"1915\"]quartz[\/pb_glossary], [pb_glossary id=\"1918\"]calcite[\/pb_glossary], malachite, azurite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Cubic<\/strong>\n\ncube-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2812\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.55_Cubic_Calcite-Galena-elm56c.jpg\"><img class=\"wp-image-2812\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.55_Cubic_Calcite-Galena-elm56c-260x300-1.jpg\" alt=\"Cubic crystals of galena, a sulfide of lead\" width=\"150\" height=\"173\"><\/a> Cubic crystals of galena[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite, galena, [pb_glossary id=\"2844\"]halite[\/pb_glossary]<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dodecahedral<\/strong>\n\n12-sided polygon shapes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2813\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.53_habit_dodecahedral_Pyrite_elbe-scaled.jpg\"><img class=\"wp-image-2813\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.53_habit_dodecahedral_Pyrite_elbe-300x195-1.jpg\" alt=\"Crystals of pyrite showing dodecahedral habit\" width=\"150\" height=\"97\"><\/a> Pyrite crystals with dodecahedral habit[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">garnet, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dendritic<\/strong>\n\nbranching crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2814\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dendrites01.jpg\"><img class=\"wp-image-2814\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Dendrites01-300x203-1.jpg\" alt=\"The mineral look like a fern. They are black and branching.\" width=\"150\" height=\"101\"><\/a> Manganese dendrites, scale in mm.[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">Mn-[pb_glossary id=\"1919\"]oxides[\/pb_glossary], copper, gold<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>[pb_glossary id=\"1932\"]Equant[\/pb_glossary]<\/strong>\n\ncrystals that do not have a long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2815\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Peridot2.jpg\"><img class=\"wp-image-209\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-272x300.jpg\" alt=\"The crystal is light green.\" width=\"150\" height=\"165\"><\/a> Large olivine crystal[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"2711\"]olivine[\/pb_glossary], garnet, [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary]<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Fibrous<\/strong>\n\nthin, very long crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2816\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tremolite_Campolungo.jpg\"><img class=\"wp-image-2816\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tremolite_Campolungo-300x186-1.jpg\" alt=\"It is white and fiberous\" width=\"150\" height=\"93\"><\/a> Tremolite, a type of amphibole[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">serpentine, [pb_glossary id=\"2713\"]amphibole[\/pb_glossary], zeolite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Layered, sheets<\/strong>\n\nstacked, very thin, flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2817\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.18_Muscovite-Albite-122887.jpg\"><img class=\"wp-image-2817\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.18_Muscovite-Albite-122887-300x254-1.jpg\" alt=\"Sheets of muscovite mica in crystal mass\" width=\"150\" height=\"127\"><\/a> Sheet crystals of muscovite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"1914\"]mica [\/pb_glossary]([pb_glossary id=\"1914\"]biotite[\/pb_glossary], [pb_glossary id=\"1914\"]muscovite[\/pb_glossary], etc.)<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Lenticular\/platy<\/strong>\n\ncrystals that are [pb_glossary id=\"2591\"]plate[\/pb_glossary]-like<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2818\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-Wulfenite-tcw15b.jpg\"><img class=\"wp-image-2818\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-Wulfenite-tcw15b-251x300-1.jpg\" alt=\"The orange wulfenite is bladed\" width=\"150\" height=\"179\"><\/a> Orange wulfenite on calcite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">selenite roses, wulfenite, [pb_glossary id=\"1918\"]calcite[\/pb_glossary]<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Hexagonal<\/strong>\n\ncrystals with six sides<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_3687\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite-1.jpg\"><img class=\"wp-image-213 size-thumbnail\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Hanksite-1-150x150.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"150\" height=\"150\"><\/a> Hexagonal hanksite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"1915\"]quartz[\/pb_glossary], hanksite, corundum<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>[pb_glossary id=\"1933\"]Massive[\/pb_glossary]\/granular<\/strong>\n\nCrystals with no obvious shape, microscopic crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2789\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"wp-image-2789\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"150\" height=\"128\"><\/a> Limonite, a hydrated oxide of iron[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">limonite, pyrite, azurite, bornite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Octahedral<\/strong>\n\n4-sided double pyramid crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2819\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90.jpg\"><img class=\"wp-image-2819\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90-300x182-1.jpg\" alt=\"Perfedt octahedral cleavage in fluorite generates octagon-shaped cleavage flakes.\" width=\"150\" height=\"91\"><\/a> Octagonal cleavage in fluorite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">diamond, fluorite, magnetite, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Prismatic\/columnar<\/strong>\n\nvery long, cylindrical crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2820\" align=\"aligncenter\" width=\"142\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tourmaline.jpg\"><img class=\"size-medium wp-image-2820\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tourmaline-142x300-1.jpg\" alt=\"The mineral is a long cylinder.\" width=\"142\" height=\"300\"><\/a> Columnar tourmaline[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">tourmaline, beryl, barite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Radiating<\/strong>\n\ncrystals that grow from a point and fan out<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2821\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pyrophyllite-236595.jpg\"><img class=\"wp-image-2821\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Pyrophyllite-236595-217x300-1.jpg\" alt=\"The mineral is orange\" width=\"150\" height=\"207\"><\/a> Pyrophyllite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite \"suns\", pyrophyllite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Rhombohedral<\/strong>\n\ncrystals shaped like slanted cubes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2785\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"wp-image-2785\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"150\" height=\"183\"><\/a> Calcite crystal in shape of rhomb.[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"1918\"]calcite[\/pb_glossary], dolomite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tabular\/blocky\/stubby<\/strong>\n\nsharp-sided crystals with no long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2770\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"150\" height=\"116\"><\/a> Crystals of diopside, a member of the pyroxene family[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">[pb_glossary id=\"1916\"]feldspar[\/pb_glossary], [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary], [pb_glossary id=\"1918\"]calcite[\/pb_glossary]<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tetrahedral<\/strong>\n\nthree-sided, pyramid-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n\n[caption id=\"attachment_2822\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg\"><img class=\"wp-image-2822\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tetrahedrite-Chalcopyrite-Sphalerite-251531-300x218-1.jpg\" alt=\"The dark brown mineral is triangular\" width=\"150\" height=\"109\"><\/a> Tetrahedrite[\/caption]<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">magnetite, spinel, tetrahedrite<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n&nbsp;\n\n[caption id=\"attachment_2824\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/GypsumStriations.jpg\"><img class=\"wp-image-2824\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/GypsumStriations-251x300-1.jpg\" alt=\"The mineral has many parallel lines on it\" width=\"150\" height=\"179\"><\/a> Gypsum with striations[\/caption]\n\n&nbsp;\n\n[caption id=\"attachment_2823\" align=\"alignright\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Staurolite-62645.jpg\"><img class=\"wp-image-2823\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Staurolite-62645-279x300-1.jpg\" alt=\"The brown minerals are replicated in different directions\" width=\"150\" height=\"161\"><\/a> Twinned staurolite[\/caption]\n\nAnother [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary] that may be used to identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] is striations, which are dark and light parallel lines on a crystal face. Twinning is another, which occurs when the crystal structure replicates in mirror images along certain directions in the crystal.\n\n[caption id=\"attachment_2825\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"size-medium wp-image-2825\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a> Striations on plagioclase[\/caption]\n\n&nbsp;\n\nStriations and twinning are related properties in some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] including [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] [pb_glossary id=\"1916\"]feldspar[\/pb_glossary]. Striations are optical lines on a cleavage surface. Because of twinning in the crystal, striations show up on one of the two cleavage faces of the [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] crystal.\n<h3><b>3.5.5 Cleavage and Fracture<\/b><\/h3>\n[pb_glossary id=\"2687\"]Minerals[\/pb_glossary] often show characteristic patterns of breaking along specific cleavage planes or show characteristic [pb_glossary id=\"1934\"]fracture[\/pb_glossary] patterns. Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as reflective surfaces on the crystal, as parallel cracks that penetrate into the crystal, or show on the edge or side of the crystal as a series of steps like rice [pb_glossary id=\"3162\"]terraces[\/pb_glossary]. Cleavage arises in crystals where the atomic [pb_glossary id=\"2703\"]bonds[\/pb_glossary] between atomic layers are weaker along some directions than others, meaning they will break preferentially along these planes.\u00a0Because they develop on atomic surfaces in the crystal, cleavage planes are optically smooth and reflect light, although the actual break on the crystal may appear jagged or uneven. In such cleavages, the cleavage surface may appear like rice [pb_glossary id=\"3162\"]terraces[\/pb_glossary] on a mountainside that all reflect sunlight from a particular sun angle. Some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] have a strong cleavage, some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] only have weak cleavage or do not typically demonstrate cleavage.\n\n[caption id=\"attachment_2826\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.57_conchoidal_Citrine-sample2.jpg\"><img class=\"size-medium wp-image-2826\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.57_conchoidal_Citrine-sample2-300x225-1.jpg\" alt=\"A specimen of a variety of quartz showing conchoidal fracture\" width=\"300\" height=\"225\"><\/a> Citrine, a variety of quartz showing conchoidal fracture[\/caption]\n\nFor example, [pb_glossary id=\"1915\"]quartz[\/pb_glossary] and [pb_glossary id=\"2711\"]olivine[\/pb_glossary] rarely show cleavage and typically break into [pb_glossary id=\"1935\"]conchoidal[\/pb_glossary] [pb_glossary id=\"1934\"]fracture[\/pb_glossary] patterns.\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n[caption id=\"attachment_2827\" align=\"alignleft\" width=\"452\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/cryview_graphite_v1.gif\"><img class=\"wp-image-2827 size-full\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/cryview_graphite_v1.gif\" alt=\"Structure of graphite, showing single carbon layers with weak bonds holding them together\" width=\"452\" height=\"504\"><\/a> Graphite showing layers of carbon atoms separated by a gap with weak bonds holding the layers together.[\/caption]\n\nGraphite has its carbon atoms arranged into layers with relatively strong [pb_glossary id=\"2703\"]bonds[\/pb_glossary] within the layer and very weak [pb_glossary id=\"2703\"]bonds[\/pb_glossary] between the layers.\u00a0 Thus graphite cleaves readily between the layers and the layers slide easily over one another giving graphite its lubricating quality.\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n[pb_glossary id=\"2687\"]Mineral[\/pb_glossary] [pb_glossary id=\"1934\"]fracture[\/pb_glossary] surfaces may be rough and uneven or they may be show [pb_glossary id=\"1935\"]conchoidal[\/pb_glossary] [pb_glossary id=\"1934\"]fracture[\/pb_glossary]. Uneven [pb_glossary id=\"1934\"]fracture[\/pb_glossary] patterns are described as irregular, splintery, fibrous. A conchoidal fracture has a smooth, curved surface like a shallow bowl or conch shell, often with curved ridges. Natural [pb_glossary id=\"1181\"]volcanic[\/pb_glossary] glass, called [pb_glossary id=\"1947\"]obsidian[\/pb_glossary], breaks with this characteristic [pb_glossary id=\"1935\"]conchoidal[\/pb_glossary] pattern\n\n&nbsp;\n\n[caption id=\"attachment_2828\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.64_galena_cleavage_Argentiferous_Galena-458851.jpg\"><img class=\"wp-image-2828 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.64_galena_cleavage_Argentiferous_Galena-458851-300x261-1.jpg\" alt=\"Specimen of galena showing cubic cleavage\" width=\"300\" height=\"261\"><\/a> Cubic cleavage of galena; note how the cleavage surfaces show up as different but parallel layers in the crystal.[\/caption]\n\n&nbsp;\n\nTo work with cleavage, it is important to remember that cleavage is a result of [pb_glossary id=\"2703\"]bonds[\/pb_glossary] separating along planes of atoms in the crystal structure. On some [pb_glossary id=\"2687\"]minerals[\/pb_glossary], <strong>cleavage planes<\/strong> may be confused with crystal faces. This will usually not be an issue for crystals of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] that grew together within rocks. The act of breaking the rock to expose a fresh face will most likely break the crystals along cleavage planes. Some cleavage planes are parallel with crystal faces but many are not.\u00a0Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as parallel cracks that penetrate into the crystal (see [pb_glossary id=\"2713\"]amphibole[\/pb_glossary] below), or show on the edge or side of the crystal as a series of steps like rice [pb_glossary id=\"3162\"]terraces[\/pb_glossary]. For some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] characteristic [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary] is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. [pb_glossary id=\"2687\"]Minerals[\/pb_glossary] grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces (see [pb_glossary id=\"1915\"]quartz[\/pb_glossary] below).\n\n[caption id=\"attachment_2829\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a> Freely growing quartz crystals showing crystal faces[\/caption]\n\n<span style=\"font-weight: 400\">In some [pb_glossary id=\"2687\"]minerals[\/pb_glossary], distinguishing cleavage planes from crystal faces may be challenging for the student. Understanding the nature of cleavage and referring to the number of cleavage planes and cleavage angles on identification keys should provide the student with enough information to distinguish cleavages from crystal faces. Cleavage planes may show as multiple parallel cracks or flat surfaces on the crystal. Cleavage planes may be expressed as a series of steps like terraced rice paddies. See the cleavage surfaces on galena above or [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] below. Cleavage planes arise from the tendency of [pb_glossary id=\"2687\"]mineral[\/pb_glossary] crystals to break along specific planes of weakness within the crystal favored by atomic arrangements. The number of cleavage planes, the quality of the cleavage surfaces, and the angles between them are diagnostic for many [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and cleavage is one of the most useful properties for identifying [pb_glossary id=\"2687\"]minerals[\/pb_glossary]. Learning to recognize cleavage is an especially important and useful skill in studying [pb_glossary id=\"2687\"]minerals[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_2830\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.61_Cleavage_steps_in_wollastonite.jpg\"><img class=\"size-medium wp-image-2830\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.61_Cleavage_steps_in_wollastonite-300x224-1.jpg\" alt=\"Image of wollastonite, a crystal showing step-like cleavage on one side. All steps are along the same direction of cleavage.\" width=\"300\" height=\"224\"><\/a> Steps of cleavage along the same cleavage direction[\/caption]\n\n&nbsp;\n\n[caption id=\"attachment_2831\" align=\"alignleft\" width=\"220\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.63_cleavage_in_Amphibole.jpg\"><img class=\"wp-image-2831\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.63_cleavage_in_Amphibole-295x300-1.jpg\" alt=\"Photomicrograph showing 120\/60 degree cleavage in amphibole\" width=\"220\" height=\"224\"><\/a> Photomicrograph showing 120\/60 degree cleavage within a grain of amphibole[\/caption]\n\n&nbsp;\n\nAs an identification property of [pb_glossary id=\"2687\"]minerals[\/pb_glossary], cleavage is usually given in terms of the quality of the cleavage (perfect, imperfect, or none), the number of cleavage surfaces, and the angles between the surfaces.\u00a0The most common number of cleavage plane directions in the common rock-forming [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are: one perfect cleavage (as in [pb_glossary id=\"1914\"]mica[\/pb_glossary]), two cleavage planes (as in [pb_glossary id=\"1916\"]feldspar[\/pb_glossary], [pb_glossary id=\"2712\"]pyroxene[\/pb_glossary], and [pb_glossary id=\"2713\"]amphibole[\/pb_glossary]), and three cleavage planes (as in [pb_glossary id=\"2844\"]halite[\/pb_glossary], [pb_glossary id=\"1918\"]calcite[\/pb_glossary], and galena). One perfect cleavage (as in [pb_glossary id=\"1914\"]mica[\/pb_glossary]) develops on the top and bottom of the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] specimen with many parallel cracks showing on the sides but no angle of intersection. Two cleavage planes intersect at an angle. Common cleavage angles are 60\u00b0, 75\u00b0, 90\u00b0, and 120\u00b0.\u00a0 [pb_glossary id=\"2713\"]Amphibole[\/pb_glossary] has two cleavage planes at\u00a060\u00b0 and\u00a0120\u00b0. Galena and [pb_glossary id=\"2844\"]halite[\/pb_glossary] have three cleavage planes at 90\u00b0 (cubic cleavage). [pb_glossary id=\"1918\"]Calcite[\/pb_glossary] cleaves readily in three directions producing a cleavage figure called a rhomb that looks like a cube squashed over toward one corner giving rise to the approximately 75\u00b0 cleavage angles. [pb_glossary id=\"2712\"]Pyroxene[\/pb_glossary] has an imperfect cleavage with two planes at 90\u00b0.\n\n<strong>Cleavages on common rock-forming [pb_glossary id=\"2687\"]minerals[\/pb_glossary]<\/strong>\n<ul>\n \t<li>[pb_glossary id=\"1915\"]Quartz[\/pb_glossary]\u2014none ([pb_glossary id=\"1935\"]conchoidal[\/pb_glossary] [pb_glossary id=\"1934\"]fracture[\/pb_glossary])<\/li>\n \t<li>[pb_glossary id=\"2711\"]Olivine[\/pb_glossary]\u2014none ([pb_glossary id=\"1935\"]conchoidal[\/pb_glossary] [pb_glossary id=\"1934\"]fracture[\/pb_glossary])<\/li>\n \t<li>[pb_glossary id=\"1914\"]Mica[\/pb_glossary]\u20141 perfect<\/li>\n \t<li>[pb_glossary id=\"1916\"]Feldspar[\/pb_glossary]\u20142 perfect at 90\u00b0<\/li>\n \t<li>[pb_glossary id=\"2712\"]Pyroxene[\/pb_glossary]\u20142 imperfect at 90\u00b0<\/li>\n \t<li>[pb_glossary id=\"2713\"]Amphibole[\/pb_glossary]\u20142 perfect at 60\u00b0\/120\u00b0<\/li>\n \t<li>[pb_glossary id=\"1918\"]Calcite[\/pb_glossary]\u20143 perfect at approximately 75\u00b0<\/li>\n \t<li>[pb_glossary id=\"2844\"]Halite[\/pb_glossary], galena, pyrite\u20143 perfect at 90\u00b0<\/li>\n<\/ul>\n<h3><b>3.5.6 Special Properties <\/b><\/h3>\n[caption id=\"attachment_2832\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ulexit_Fernsehstein.jpg\"><img class=\"size-thumbnail wp-image-2832\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ulexit_Fernsehstein-150x150-1.jpg\" alt=\"The words on the page are projected upwards onto the mineral\" width=\"150\" height=\"150\"><\/a> A demonstration of ulexite's image projection[\/caption]\n\n<span style=\"font-weight: 400\">Special properties are unique and identifiable characteristics used to identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] or that allow some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] to be used for special purposes.\u00a0<\/span>Ulexite has a fiber-optic property that can project images through the crystal like a high-definition television screen (see figure). A simple identifying special property is taste, such as the salty flavor of [pb_glossary id=\"2844\"]halite[\/pb_glossary] or common table salt (NaCl). Sylvite is potassium chloride (KCl) and has a more bitter taste.\n\n[caption id=\"attachment_2833\" align=\"alignright\" width=\"225\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Latrobe_gold_nugget_Natural_History_Museum.jpg\"><img class=\"size-medium wp-image-2833\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Latrobe_gold_nugget_Natural_History_Museum-225x300-1.jpg\" alt=\"The nugget is gold\" width=\"225\" height=\"300\"><\/a> Native gold has one of the highest specific gravities.[\/caption]\n\n&nbsp;\n\nAnother property geologists may use to identify [pb_glossary id=\"2687\"]minerals[\/pb_glossary] is a property related to density called <strong>[pb_glossary id=\"1937\"]specific gravity[\/pb_glossary]<\/strong>. [pb_glossary id=\"1937\"]Specific gravity[\/pb_glossary] measures the weight of a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] specimen relative to the weight of an equal volume of water. The value is expressed as a ratio between the [pb_glossary id=\"2687\"]mineral[\/pb_glossary] and water weights. To measure [pb_glossary id=\"1937\"]specific gravity[\/pb_glossary], a [pb_glossary id=\"2687\"]mineral[\/pb_glossary] specimen is first weighed in grams then submerged in a graduated cylinder filled with pure water at room [pb_glossary id=\"2689\"]temperature[\/pb_glossary]. The rise in water level is noted using the cylinder\u2019s graduated scale. Since the weight of water at room [pb_glossary id=\"2689\"]temperature[\/pb_glossary] is 1 gram per cubic centimeter, the ratio of the two weight numbers gives the [pb_glossary id=\"1937\"]specific gravity[\/pb_glossary]. [pb_glossary id=\"1937\"]Specific gravity[\/pb_glossary] is easy to measure in the laboratory but is less useful for [pb_glossary id=\"2687\"]mineral[\/pb_glossary] identification in the field than other more easily observed properties, except in a few rare cases such as the very dense galena or [pb_glossary id=\"1924\"]native[\/pb_glossary] gold. The high density of these [pb_glossary id=\"2687\"]minerals[\/pb_glossary] gives rise to a [pb_glossary id=\"2647\"]qualitative[\/pb_glossary] property called \u201cheft.\u201d Experienced geologists can roughly assess [pb_glossary id=\"1937\"]specific gravity[\/pb_glossary] by heft, a [pb_glossary id=\"2645\"]subjective[\/pb_glossary] quality of how heavy the specimen feels in one\u2019s hand relative to its size.\n\nA simple test for identifying [pb_glossary id=\"1918\"]calcite[\/pb_glossary] and dolomite is to drop a bit of dilute hydrochloric acid (10-15% HCl) on the specimen. If the acid drop effervesces or fizzes on the surface of the rock, the specimen is [pb_glossary id=\"1918\"]calcite[\/pb_glossary]. If it does not, the specimen is scratched to produce a small amount of powder and test with acid again. If the acid drop fizzes slowly on the powdered [pb_glossary id=\"2687\"]mineral[\/pb_glossary], the specimen is dolomite. The difference between these two [pb_glossary id=\"2687\"]minerals[\/pb_glossary] can be seen in the video. Geologists who work with [pb_glossary id=\"1917\"]carbonate[\/pb_glossary] rocks carry a small dropper bottle of dilute HCl in their field kit. Vinegar, which contains acetic acid, can be used for this test and is used to distinguish non-[pb_glossary id=\"1918\"]calcite[\/pb_glossary] [pb_glossary id=\"2176\"]fossils[\/pb_glossary] from [pb_glossary id=\"2851\"]limestone[\/pb_glossary]. While acidic, vinegar produces less of a fizzing reaction because acetic acid is a weaker acid.\n\n[embed]https:\/\/www.youtube.com\/embed\/DX6ZMPbA09U[\/embed]\n\n[caption id=\"attachment_3750\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-and-Dolomite-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-228\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[caption id=\"attachment_2834\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Magnetite_Lodestone.jpg\"><img class=\"size-medium wp-image-2834\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Magnetite_Lodestone-300x200-1.jpg\" alt=\"The paperclip is sticking up into the air.\" width=\"300\" height=\"200\"><\/a> Paperclips attach to lodestone (magnetite).[\/caption]\n\nSome iron-[pb_glossary id=\"1919\"]oxide[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are magnetic and are attracted to magnets. A common name for a naturally magnetic iron [pb_glossary id=\"1919\"]oxide[\/pb_glossary] is <strong>lodestone<\/strong>. Others include magnetite (Fe3O<sub>4<\/sub>) and ilmenite (FeTiO<sub>3<\/sub>). Magnetite is strongly attracted to magnets and can be magnetized. Ilmenite and some types of hematite are weakly magnetic.\n\n[caption id=\"attachment_2825\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"wp-image-2825 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a> Iridescence on plagioclase; also showing striations on the cleavage surface[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">Some [pb_glossary id=\"2687\"]minerals[\/pb_glossary] and mineraloids scatter light via a phenomenon called <strong>iridescence<\/strong>. This property occurs in labradorite (a variety of [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary]) and opal. It is also seen in biologically created substances like pearls and seashells. Cut diamonds show iridescence and the jeweler\u2019s diamond cut is designed to maximize this property.<\/span>\n\n[caption id=\"attachment_2835\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD.jpg\"><img class=\"size-medium wp-image-2835\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD-300x217-1.jpg\" alt=\"Image showing exsolution lamellae in potassium feldspar. These are separations of sodium feldspar from potassium feldspar within the crystal, not striations.\" width=\"300\" height=\"217\"><\/a> Exsolution lamellae within potassium feldspar[\/caption]\n\n<strong>Striations<\/strong> on [pb_glossary id=\"2687\"]mineral[\/pb_glossary] cleavage faces are an optical property that can be used to separate [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] from potassium [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] ([pb_glossary id=\"1916\"]K-spar[\/pb_glossary]). A process called twinning creates parallel zones in the crystal that are repeating mirror images. The actual cleavage angle in [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary] is slightly different than 90<sup>o<\/sup> and the alternating mirror images in these twinned zones produce a series of parallel lines on one of [pb_glossary id=\"1916\"]plagioclase[\/pb_glossary]\u2019s two cleavage faces. Light reflects off these twinned lines at slightly different angles which then appear as light and dark lines called striations on the cleavage surface.\u00a0Potassium [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] does not exhibit twinning or striations but may show linear features called <strong>exsolution lamellae<\/strong>, also known as perthitic [pb_glossary id=\"2925\"]lineation[\/pb_glossary] or simply perthite. Because sodium and potassium do not fit into the same [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] crystal structure, the lines are created by small amounts of sodium [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] (albite) separating from the dominant potassium [pb_glossary id=\"1916\"]feldspar[\/pb_glossary] ([pb_glossary id=\"1916\"]K-spar[\/pb_glossary]) within the crystal structure. The two different [pb_glossary id=\"1916\"]feldspars[\/pb_glossary] crystallize out into roughly parallel zones within the crystal, which are seen as these linear markings.\n\n[caption id=\"attachment_2793\" align=\"alignright\" width=\"244\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a> Fluorite. B shows fluorescence of fluorite under UV light[\/caption]\n\nOne of the most interesting special [pb_glossary id=\"2687\"]mineral[\/pb_glossary] properties is <strong>fluorescence<\/strong>. Certain [pb_glossary id=\"2687\"]minerals[\/pb_glossary], or \u00a0trace [pb_glossary id=\"2700\"]elements[\/pb_glossary] within them, give off visible light when exposed to ultraviolet radiation or black light. Many [pb_glossary id=\"2687\"]mineral[\/pb_glossary] exhibits have a fluorescence room equipped with black lights so this property can be observed. An even rarer optical property is phosphorescence. <strong>Phosphorescent<\/strong> [pb_glossary id=\"2687\"]minerals[\/pb_glossary] absorb light and then slowly release it, much like a glow-in-the-dark sticker.\n\n&nbsp;\n\n&nbsp;\n<h3><\/h3>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"21\"]\n\n[caption id=\"attachment_3749\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.5-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-231\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 3.5 via this QR Code.[\/caption]\n<h2><span style=\"font-size: 18pt\"><strong>Summary<\/strong><\/span><\/h2>\n[pb_glossary id=\"2687\"]Minerals[\/pb_glossary] are the building blocks of rocks and essential to understanding geology. [pb_glossary id=\"2687\"]Mineral[\/pb_glossary] properties are determined by their atomic [pb_glossary id=\"2703\"]bonds[\/pb_glossary]. Most [pb_glossary id=\"2687\"]minerals[\/pb_glossary] begin in a fluid, and either crystallize out of cooling [pb_glossary id=\"2672\"]magma[\/pb_glossary] or [pb_glossary id=\"2707\"]precipitate[\/pb_glossary] as ions and molecules out of a [pb_glossary id=\"2706\"]saturated[\/pb_glossary] [pb_glossary id=\"2705\"]solution[\/pb_glossary]. The [pb_glossary id=\"2709\"]silicates[\/pb_glossary] are largest group of [pb_glossary id=\"2687\"]minerals[\/pb_glossary] on Earth, by number of varieties and relative quantity, making up a large portion of the [pb_glossary id=\"2580\"]crust[\/pb_glossary] and [pb_glossary id=\"2586\"]mantle[\/pb_glossary]. Based on the [pb_glossary id=\"2710\"]silicon-oxygen tetrahedra[\/pb_glossary], the crystal structure of [pb_glossary id=\"2709\"]silicates[\/pb_glossary] reflects the fact that silicon and oxygen are the top two of Earth\u2019s most abundant [pb_glossary id=\"2700\"]elements[\/pb_glossary]. Non-[pb_glossary id=\"2709\"]silicate[\/pb_glossary] [pb_glossary id=\"2687\"]minerals[\/pb_glossary] are also economically important, and providing many types of construction and manufacturing materials. [pb_glossary id=\"2687\"]Minerals[\/pb_glossary] are identified by their unique physical properties, including [pb_glossary id=\"1925\"]luster[\/pb_glossary], color, [pb_glossary id=\"1926\"]streak[\/pb_glossary], [pb_glossary id=\"1927\"]hardness[\/pb_glossary], [pb_glossary id=\"1928\"]crystal habit[\/pb_glossary], [pb_glossary id=\"1934\"]fracture[\/pb_glossary], cleavage, and special properties.\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n[h5p id=\"22\"]\n\n[caption id=\"attachment_3748\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ch.3-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-232\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the review quiz for Chapter 3 via this QR Code.[\/caption]\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n \t<li class=\"csl-entry\">Clarke, F.W.H.S.W., 1927, The [pb_glossary id=\"2831\"]Composition[\/pb_glossary] of the Earth\u2019s [pb_glossary id=\"2580\"]Crust[\/pb_glossary]: Professional Paper, United States Geological Survey, Professional Paper.<\/li>\n \t<li class=\"csl-entry\">Gordon, L.M., and Joester, D., 2011, Nanoscale chemical [pb_glossary id=\"3096\"]tomography[\/pb_glossary] of buried organic-inorganic interfaces in the chiton tooth: Nature, v. 469, no. 7329, p. 194\u2013197.<\/li>\n \t<li class=\"csl-entry\">Hans Wedepohl, K., 1995, The [pb_glossary id=\"2831\"]composition[\/pb_glossary] of the [pb_glossary id=\"2575\"]continental crust[\/pb_glossary]: Geochim. Cosmochim. Acta, v. 59, no. 7, p. 1217\u20131232.<\/li>\n \t<li class=\"csl-entry\">Lambeck, K., 1986, Planetary evolution: [pb_glossary id=\"2848\"]banded iron[\/pb_glossary] [pb_glossary id=\"2960\"]formations[\/pb_glossary]: v. 320, no. 6063, p. 574\u2013574.<\/li>\n \t<li class=\"csl-entry\">[pb_glossary id=\"3345\"]metallic[\/pb_glossary] [pb_glossary id=\"2703\"]bond[\/pb_glossary] | chemistry.<\/li>\n \t<li class=\"csl-entry\">Scerri, E.R., 2007, The Periodic Table: Its Story and Its Significance: Oxford University Press, USA.<\/li>\n \t<li class=\"csl-entry\">Thomson, J.J., 1897, XL. Cathode Rays: Philosophical Magazine Series 5, v. 44, no. 269, p. 293\u2013316.<\/li>\n \t<li class=\"csl-entry\">Trenn, T.J., Geiger, H., Marsden, E., and Rutherford, E., 1974, The Geiger-Marsden Scattering Results and Rutherford\u2019s Atom, July 1912 to July 1913: The Shifting Significance of Scientific Evidence: Isis, v. 65, no. 1, p. 74\u201382.<\/li>\n<\/ol>\n<\/div>\n<span style=\"font-weight: 400\">\u00a0<\/span>\n\n&nbsp;\n\n&nbsp;","rendered":"<figure id=\"attachment_2752\" aria-describedby=\"caption-attachment-2752\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cristales_cueva_de_Naica.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2752 size-large\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/Cristales_cueva_de_Naica-1024x683-1.jpg\" alt=\"The crystals are huge!\" width=\"1024\" height=\"683\" \/><\/a><figcaption id=\"caption-attachment-2752\" class=\"wp-caption-text\">These selenite (gypsum) crystals, found in The Cave of the Crystals in Naica, Mexico, has some of the largest minerals ever found. The largest crystal found here is 39 feet (12 meters) and 55 tones.<\/figcaption><\/figure>\n<h1>3 Minerals<\/h1>\n<p><strong>KEY<\/strong><b> CONCEPTS<\/b><\/p>\n<p><b>At the end of this chapter, students should be able to:<\/b><\/p>\n<ul>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Define <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the basic structure of the atom.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Derive basic atomic information from the Periodic Table of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">Elements<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonding<\/a> related to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the main ways <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> form.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a> and how it forms common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">List common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">sulfate<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> groups.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> using physical properties and identification tables. <\/span><\/li>\n<\/ul>\n<p>The term \u201c<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>\u201d as used in nutrition labels and pharmaceutical products is not the same as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> in a geological sense. In geology, the classic definition of a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a><\/strong> is: 1) naturally occurring, 2) inorganic, 3) solid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a>, 4) regular crystal structure, and 5) defined chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a>. Some natural substances technically should not be considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, but are included by exception. For example, water and mercury are liquid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a>. Both are considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> because they were classified before the room-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> rule was accepted as part of the definition. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a> is quite often formed by organic processes, but is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> because it is widely found and geologically important. Because of these discrepancies, the International Mineralogical Association in 1985 amended the definition to: \u201cA <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> is an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> or chemical compound that is normally crystalline and that has been formed as a result of geological processes.\u201d This means that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> in the shell of a clam is not considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>. But once that clam shell undergoes burial, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2827\">diagenesis<\/a>, or other geological processes, then the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>. Typically, substances like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2856\">coal<\/a>, pearl, opal, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1947\">obsidian<\/a> that do not fit the definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> are called mineraloids.<\/p>\n<p>A <strong>rock<\/strong> is a substance that contains one or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> or mineraloids. As is discussed in later chapters, there are three types of rocks <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> (rocks crystallizing from molten material), sedimentary (rocks <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of products of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1204\">mechanical weathering<\/a> (sand, gravel, etc.) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2812\">chemical weathering<\/a> (things <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitated<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a>), and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> (rocks produced by alteration of other rocks by heat and pressure.<\/p>\n<h2><span style=\"font-weight: 400\">3.1 Chemistry of Minerals<\/span><\/h2>\n<p>Rocks are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> that have a specific chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a>.\u00a0 To understand <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> chemistry, it is essential to examine the fundamental unit of all matter, the atom.<\/p>\n<h3><b>3.1.1 The Atom<\/b><\/h3>\n<figure id=\"attachment_2753\" aria-describedby=\"caption-attachment-2753\" style=\"width: 283px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.1-Electron_cloud_model_of_atom.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2753\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/03.1-Electron_cloud_model_of_atom-283x300-1.jpg\" alt=\"Image of atom with defined nucleus and electrons surrounding it in a cloud with concentrations of electrons in energy shells\" width=\"283\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2753\" class=\"wp-caption-text\">Electron cloud model of the atom<\/figcaption><\/figure>\n<p>Matter is made of atoms. Atoms consists of subatomic particles\u2014<strong>protons<\/strong>, <strong>neutrons<\/strong>, and <strong>electrons<\/strong>. A simple model of the atom has a central nucleus <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of protons, which have positive charges, and neutrons which have no charge. A cloud of negatively charged electrons surrounds the nucleus, the number of electrons equaling the number of protons thus balancing the positive charge of the protons for a neutral atom. Protons and neutrons each have a mass number of 1. The mass of an electron is less than\u00a01\/1000<sup>th<\/sup>\u00a0that of a proton or neutron, meaning most of the atom\u2019s mass is in the nucleus.<\/p>\n<h3><b>3.1.2 Periodic Table of the Elements<\/b><\/h3>\n<p>Matter is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> which are atoms that have a specific number of protons in the nucleus. This number of protons is called the <strong>Atomic Number<\/strong> for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>. For example, an oxygen atom has 8 protons and an iron atom has 26 protons. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> cannot be broken down chemically into a simpler form and retains unique chemical and physical properties. Each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> behaves in a unique manner in nature. This uniqueness led scientists to develop a periodic table of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>, a tabular arrangement of all known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> listed in order of their atomic number.<\/p>\n<figure id=\"attachment_2754\" aria-describedby=\"caption-attachment-2754\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Periodic_Table-02-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-2754\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/Periodic_Table-02-1024x795-1.jpg\" alt=\"The Periodic Table of the Elements showing all elements with their chemical symbols, atomic weight, and atomic number.\" width=\"1024\" height=\"795\" \/><\/a><figcaption id=\"caption-attachment-2754\" class=\"wp-caption-text\">The Periodic Table of the Elements<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The first arrangement of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> into a periodic table was done by Dmitri Mendeleev in 1869 using the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> known at the time<\/span><span style=\"font-weight: 400\">. In the periodic table, each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> has a chemical symbol, name, atomic number, and atomic mass. The chemical symbol is an abbreviation for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>, often derived from a Latin or Greek name for the substance<\/span><span style=\"font-weight: 400\">. The atomic number is the number of protons in the nucleus. The atomic mass is the number of protons and neutrons in the nucleus, each with a mass number of one. Since the mass of electrons is so much less than the protons and neutrons, the atomic mass is effectively the number of protons plus neutrons. <\/span><\/p>\n<figure id=\"attachment_2755\" aria-describedby=\"caption-attachment-2755\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3a_Formation_of_Carbon14_from_Nitrogen14.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2755\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/3.3a_Formation_of_Carbon14_from_Nitrogen14-300x123-1.jpg\" alt=\"\" width=\"300\" height=\"123\" \/><\/a><figcaption id=\"caption-attachment-2755\" class=\"wp-caption-text\">Formation of Carbon 14 from Nitrogen 14<\/figcaption><\/figure>\n<p>The atomic mass of natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> represents an average mass of the atoms comprising that substance in nature and is usually not a whole number as seen on the periodic table, meaning that an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> exists in nature with atoms having different numbers of neutrons. The differing number of neutrons affects the mass of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> in nature and the atomic mass number represents this average. This gives rise to the concept of\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2701\">isotope<\/a><strong>.\u00a0<\/strong><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2701\">Isotopes<\/a> <\/strong>are forms of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> with the same number of protons but different numbers of neutrons. There are usually several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2701\">isotopes<\/a> for a particular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>. For example, 98.9% of carbon atoms have 6 protons and 6 neutrons. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2701\">isotope<\/a> of carbon is called carbon-12 (<sup>12<\/sup>C). A few carbon atoms, carbon-13 (<sup>13<\/sup>C), have 6 protons and 7 neutrons. A trace amount of carbon atoms, carbon-14 (<sup>14<\/sup>C), has 6 protons and 8 neutrons.<\/p>\n<figure id=\"attachment_2756\" aria-describedby=\"caption-attachment-2756\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/elemental-composition-crust.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2756\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/elemental-composition-crust-300x277-1.jpg\" alt=\"Oxygen and silicon make up 3\/4ths of the chart.\" width=\"300\" height=\"277\" \/><\/a><figcaption id=\"caption-attachment-2756\" class=\"wp-caption-text\">Element abundance pie chart for Earth&#8217;s crust by Callan Bentley.<\/figcaption><\/figure>\n<p>Among the 118 known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>, the heaviest are fleeting human creations known only in high energy particle accelerators, and they decay rapidly. The heaviest naturally occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> is uranium, atomic number 92. The eight most abundant elements in Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">continental crust<\/a> are shown in Table 1<span style=\"font-weight: 400\">. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> are found in the most common rock forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<table style=\"height: 135px\">\n<tbody>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">Element<\/a><\/b><\/td>\n<td style=\"height: 15px;width: 134.797px\"><b>Symbol<\/b><\/td>\n<td style=\"height: 15px;width: 237.703px\"><b>Abundance %<\/b><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Oxygen<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">O<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">47%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Silicon<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Si<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">28%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Aluminum<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Al<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">8%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Iron<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Fe<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">5%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Calcium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Ca<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">4%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Sodium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Na<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Potassium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">K<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Magnesium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">Mg<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">2%<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em style=\"font-size: 16px;font-weight: 400\">Table 1. Eight Most Abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">Elements<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">Continental Crust<\/a> % by weight (source:\u00a0<a href=\"https:\/\/pubs.usgs.gov\/circ\/1953\/0285\/report.pdf\">USGS<\/a>). All other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> are less than 1%.<\/em><\/p>\n<h3><b>3.1.3 Chemical Bonding<\/b><\/h3>\n<figure id=\"attachment_2757\" aria-describedby=\"caption-attachment-2757\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/H2O_2D_labelled.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-145 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-300x131.png\" alt=\"The hydrogen atoms are on one side, about 105\u00b0 apart.\" width=\"300\" height=\"131\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-300x131.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-768x336.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-65x28.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-225x98.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_-350x153.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2021\/09\/H2O_2D_labelled.svg_.png 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-2757\" class=\"wp-caption-text\">A model of a water molecule, showing the bonds between the hydrogen and oxygen.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Most substances on Earth are compounds containing multiple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>. Chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonding<\/a> describes how these atoms attach with each other to form compounds, such as sodium and chlorine combining to form NaCl, common table salt. Compounds that are held together by\u00a0<\/span>chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> are called molecules. Water is a compound of hydrogen and oxygen in which two hydrogen atoms are covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with one oxygen making the water molecule. The oxygen we breathe is formed when one oxygen atom covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> with another oxygen atom to make the molecule O<sub>2<\/sub>. The subscript 2 in the chemical formula indicates the molecule contains two atoms of oxygen.<\/p>\n<p>Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are also compounds of more than one <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>. The common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> has the chemical formula CaCO<sub>3<\/sub> indicating the molecule consists of one calcium, one carbon, and three oxygen atoms.\u00a0In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, one carbon and three oxygen atoms are held together by covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> to form a <strong>molecular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a><\/strong>, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a>, which has a negative charge. Calcium as an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a><\/strong> has a positive charge of plus two. The two oppositely charged ions attract each other and combine to form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, CaCO3. The name of the chemical compound is calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a>, where calcium is Ca and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> refers to the molecular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> CO<sub>3<\/sub><sup>-2<\/sup>.<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> has the chemical formula (Mg,Fe)<sub>2<\/sub>SiO<sub>4<\/sub>, in which one silicon and four oxygen atoms are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with two atoms of either magnesium or iron.\u00a0The comma between iron (Fe) and magnesium (Mg) indicates the two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> can occupy the same location in the crystal structure and substitute for one another.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.1 Valence and Charge<\/span><\/i><\/h4>\n<p><span style=\"font-weight: 400\">The electrons around the atom\u2019s nucleus are located in shells representing different energy levels. The outermost shell is called the <strong>valence shell<\/strong>. Electrons in the valence shell are involved in chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonding<\/a>. In 1913, Niels Bohr proposed a simple model of the atom that states atoms are more stable when their outermost shell is full<\/span><span style=\"font-weight: 400\">. Atoms of most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> thus tend to gain or lose electrons so the outermost or valence shell is full. In Bohr\u2019s model, the innermost shell can have a maximum of two electrons and the second and third shells can have a maximum of eight electrons. <\/span>When the innermost shell is the valence shell, as in the case of hydrogen and helium, it obeys the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3361\">octet rule<\/a> when it is full with two electrons. For <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in higher rows, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3361\">octet rule<\/a> of eight electrons in the valence shell applies.<\/p>\n<figure id=\"attachment_2758\" aria-describedby=\"caption-attachment-2758\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.4_Carbon_dioxide_3D_ball.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2758 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.4_Carbon_dioxide_3D_ball-300x213-1.png\" alt=\"Carbon dioxide molecule with a carbon ion in the center and two oxygen ions on either side, each sharing two electrons with the carbon.\" width=\"300\" height=\"213\" \/><\/a><figcaption id=\"caption-attachment-2758\" class=\"wp-caption-text\">The carbon dioxide molecule. Since Oxygen is -2 and Carbon is +4, the two oxygens bond to the carbon to form a neutral molecule.<\/figcaption><\/figure>\n<p>The rows in the periodic table present the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in order of atomic number and the columns organize <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> with similar characteristics, such as the same number of electrons in their valence shells. Columns are often labeled from left to right with Roman numerals I to VIII, and Arabic numerals 1 through 18. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in columns I and II have 1 and 2 electrons in their respective valence shells and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in columns VI and VII have 6 and 7 electrons in their respective valence shells.<\/p>\n<p><span style=\"font-weight: 400\">In row 3 and column I, sodium (Na) has 11 protons in the nucleus and 11 electrons in three shells\u20142 electrons in the inner shell, 8 electrons in the second shell, and 1 electron in the valence shell. To maintain a full outer shell of 8 electrons per the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3361\">octet rule<\/a>, sodium readily gives up that 1 electron so there are 10 total electrons. With 11 positively charged protons in the nucleus and 10 negatively charged electrons in two shells, sodium when forming chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> is an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> with an overall net charge of +1<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<p><span style=\"font-weight: 400\">All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in column I have a single electron in their valence shell and a valence of 1.\u00a0<\/span>These other column I <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> also readily give up this single valence electron and thus become ions with a +1 charge. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">Elements<\/a> in column II readily give up 2 electrons and end up as ions with a charge of +2. Note that elements in columns I and II which readily give up their valence electrons, often form bonds with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in columns VI and VII which readily take up these electrons. \u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">Elements<\/a> in columns 3 through 15 are usually involved in covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonding<\/a>. The last column 18 (VIII) contains the <strong>noble gases<\/strong>. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> are chemically inert because the valence shell is already full with 8 electrons, so they do not gain or lose electrons. An example is the noble gas helium which has 2 valence electrons in the first shell. Its valence shell is therefore full. All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in column VIII possess full valence shells and do not form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>.<\/p>\n<p><span style=\"font-weight: 400\">As seen above, an atom with a net positive or negative charge as a result of gaining or losing electrons is called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a><\/strong>. In general the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> on the left side of the table lose electrons and become positive ions, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a> because they are attracted to the cathode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> on the right side tend to gain electrons. These are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2704\">anions<\/a> because they are attracted to the anode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> in the center of the periodic table, columns 3 through 15, do not consistently follow the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3361\">octet rule<\/a>. These are called transition <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>. A common example is iron, which has a +2 or +3 charge depending on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2818\">oxidation<\/a> state of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>. Oxidized Fe<sup>+3<\/sup> carries a +3 charge and reduced Fe<sup>+2<\/sup> is +2. These two different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2818\">oxidation<\/a> states of iron often impart dramatic colors to rocks containing their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>\u2014the oxidized form producing red colors and the reduced form producing green.<\/span><\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.2\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Ionic Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2759\" aria-describedby=\"caption-attachment-2759\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03-Sodium-chloride-3D-ionic.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2759\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03-Sodium-chloride-3D-ionic-300x284-1.png\" alt=\"Image of crystal model of halite with ions of sodium and chlorine arranged in a cubic structure.\" width=\"300\" height=\"284\" \/><\/a><figcaption id=\"caption-attachment-2759\" class=\"wp-caption-text\">Cubic arrangement of Na and Cl in Halite<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a>, also called electron-transfer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a>, are formed by the electrostatic attraction between atoms having opposite charges. Atoms of two opposite charges attract each other electrostatically and form an <strong>ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a><\/strong> in which the positive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> transfers its electron (or electrons) to the negative <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> which takes them up. Through this transfer both atoms thus achieve a full valence shell.\u00a0<\/span>For example one atom of sodium (Na<sup>+1<\/sup>) and one atom of chlorine (Cl<sup>-1<\/sup>) form an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> to make the compound sodium chloride (NaCl). This is also known as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> or common table salt. Another example is calcium (Ca<sup>+2<\/sup>) and chlorine (Cl<sup>-1<\/sup>) combining to make the compound calcium chloride (CaCl<sub>2<\/sub>). The subscript 2 indicates two atoms of chlorine are ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> to one atom of calcium.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.3\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Covalent <\/span><\/i><i><span style=\"font-weight: 400\">Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2760\" aria-describedby=\"caption-attachment-2760\" style=\"width: 249px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Covalent.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2760\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Covalent.svg_-249x300-1.png\" alt=\"Each atom is sharing electrons.\" width=\"249\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2760\" class=\"wp-caption-text\">Methane molecule<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> are usually formed between a <strong>metal<\/strong> and a <strong>nonmetal<\/strong>. Another type, called a covalent or electron-sharing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a>, commonly occurs between nonmetals. Covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> share electrons between ions to complete their valence shells. For example, oxygen (atomic number 8) has 8 electrons\u20142 in the inner shell and 6 in the valence shell. Gases like oxygen often form diatomic molecules by sharing valence electrons. In the case of oxygen, two atoms attach to each other and share 2 electrons to fill their valence shells to become the common oxygen molecule we breathe (O<sub>2<\/sub>). Methane (CH<sub>4<\/sub>) is another covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> gas. The carbon atom needs 4 electrons and each hydrogen needs 1. Each hydrogen shares its electron with the carbon to form a molecule as shown in the figure.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-17\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-17\" class=\"h5p-iframe\" data-content-id=\"17\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3754\" aria-describedby=\"caption-attachment-3754\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.1-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-149\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.1-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3754\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 28px\">3.2 Formation of Minerals<\/span><\/h2>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> form when atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> together in a crystalline arrangement. Three main ways this occurs in nature are: 1) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> directly from an aqueous (water) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> change, 2) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2674\">crystallization<\/a> from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> change, and 3) biological <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> by the action of organisms. <\/span><\/p>\n<h3><b> 3.2.1 Precipitation from aqueous solution<\/b><\/h3>\n<figure id=\"attachment_2761\" aria-describedby=\"caption-attachment-2761\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5_Hard_Water_Calcification.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2761\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.5_Hard_Water_Calcification-300x200-1.jpg\" alt=\"Encrusted calcium carbonate (lime) deposits on faucent\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-2761\" class=\"wp-caption-text\">Calcium carbonate deposits from hard water<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">Solutions<\/a> consist of ions or molecules, known as solutes, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolved<\/a> in a medium or solvent. In nature this solvent is usually water. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> can be dissolved in water, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> or table salt, which has the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a> sodium chloride, NaCl. The Na<sup>+1<\/sup> and Cl<sup>-1<\/sup> ions separate and disperse into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a>.<\/p>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">Precipitation<\/a><\/strong> is the reverse process, in which ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a> come together to form solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">Precipitation<\/a> is dependent on the concentration of ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a> and other factors such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> and pressure. The point at which a solvent cannot hold any more solute is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2706\">saturation<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">Precipitation<\/a> can occur when the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3119\">falls<\/a>, when the solute evaporates, or with changing chemical conditions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a>. An example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> in our homes is when water evaporates and leaves behind a rind of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> on faucets, shower heads, and drinking glasses.<\/p>\n<p>In nature, changes in environmental conditions may cause the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolved<\/a> in water to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> and grow into crystals or cement grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2678\">sediment<\/a> together. In Utah, deposits of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2846\">tufa<\/a> formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>-rich springs that emerged into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1700\">ice age<\/a> Lake Bonneville. Now exposed in dry valleys, this porous <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2846\">tufa<\/a> was a natural insulation used by pioneers to build their homes with a natural protection against summer heat and winter cold. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2847\">travertine<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3162\">terraces<\/a> at Mammoth Hot Springs in Yellowstone Park are another example formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> at the edges of the shallow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3174\">spring<\/a>-fed ponds.<\/p>\n<figure id=\"attachment_2762\" aria-describedby=\"caption-attachment-2762\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.6_1200px-Bonneville_Salt_Flats.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2762\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.6_1200px-Bonneville_Salt_Flats-300x197-1.jpg\" alt=\"The Bonneville Salt Flats of Utah\" width=\"300\" height=\"197\" \/><\/a><figcaption id=\"caption-attachment-2762\" class=\"wp-caption-text\">The Bonneville Salt Flats of Utah<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Another example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> occurs in the Great Salt Lake, Utah, where the concentration of sodium chloride and other salts is nearly eight times greater than in the world\u2019s oceans <\/span><span style=\"font-weight: 400\">[zotpressInText item=&#8221;{DU5CMSHJ}&#8221; format=&#8221;%num%&#8221; brackets=&#8221;yes&#8221;]<\/span><span style=\"font-weight: 400\">.\u00a0<\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3134\">Streams<\/a> carry salt ions into the lake from the surrounding mountains. With no other outlet, the water in the lake evaporates and the concentration of salt increases until <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2706\">saturation<\/a> is reached and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitate<\/a> out as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2678\">sediments<\/a>. Similar salt deposits include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> and other precipitates, and occur in other lakes like Mono Lake in California and the Dead Sea.<\/p>\n<h3><b>3.2.2 Crystallization from Magma<\/b><\/h3>\n<figure id=\"attachment_2763\" aria-describedby=\"caption-attachment-2763\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5a_Pahoehoe_toe.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2763\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.5a_Pahoehoe_toe-300x188-1.jpg\" alt=\"A lava flow\" width=\"300\" height=\"188\" \/><\/a><figcaption id=\"caption-attachment-2763\" class=\"wp-caption-text\">Lava, magma at the earth\u2019s surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Heat is energy that causes atoms in substances to vibrate. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">Temperature<\/a> is a measure of the intensity of the vibration. If the vibrations are violent enough, chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> are broken and the crystals melt releasing the ions into the melt. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">Magma<\/a> is molten rock with freely moving ions. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a> is emplaced at depth or extruded onto the surface (then called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2673\">lava<\/a>), it starts to cool and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> crystals can form.<\/p>\n<h3><b>3.2.3 Precipitation by Organisms<\/b><\/h3>\n<figure id=\"attachment_2764\" aria-describedby=\"caption-attachment-2764\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.8_Ammonite_Asteroceras.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-2764\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.8_Ammonite_Asteroceras.jpg\" alt=\"Shell of an ammonite, an extinct cephalopod, with a spiral shell in a plane.\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-2764\" class=\"wp-caption-text\">Ammonite shell made of calcium carbonate<\/figcaption><\/figure>\n<p><span style=\"font-size: 1em\">Many organisms build bones, shells, and body coverings by extracting ions from water and precipitating <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> biologically. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitated<\/a> by organisms is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, or calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> (CaCO3). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a> is often <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitated<\/a> by organisms as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3362\">polymorph<\/a> called aragonite. <\/span><strong style=\"font-size: 1em\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3362\">Polymorphs<\/a><\/strong><span style=\"font-size: 1em\"> are crystals with the same chemical formula but different crystal structures. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2883\">Marine<\/a> invertebrates such as corals and clams <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitate<\/a> aragonite or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> for their shells and structures. Upon death, their hard parts accumulate on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2885\">ocean floor<\/a> as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2678\">sediments<\/a>, and eventually may become the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2683\">sedimentary rock<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a>. Though <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a> can form inorganically, the vast majority is formed by this biological process. Another example is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2883\">marine<\/a> organisms called radiolaria, which are zooplankton that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitate<\/a> silica for their microscopic external shells. When the organisms die, the shells accumulate on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2885\">ocean floor<\/a> and can form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2683\">sedimentary rock<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2849\">chert<\/a>. An example of biologic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2222\">vertebrate<\/a> world is bone, which is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> mostly of a type of apatite, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">phosphate<\/a> group. The apatite found in bones contains calcium and water in its structure and is called hydroxycarbonate apatite, Ca<\/span><sub>5<\/sub><span style=\"font-size: 1em\">(PO<\/span><sub>4<\/sub><span style=\"font-size: 1em\">)<\/span><sub>3<\/sub><span style=\"font-size: 1em\">(OH).\u00a0 As mentioned above, such substances are not technically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> until the organism dies and these hard parts become <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2176\">fossils<\/a>.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-18\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-18\" class=\"h5p-iframe\" data-content-id=\"18\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3753\" aria-describedby=\"caption-attachment-3753\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.2-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-154\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.2-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3753\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.3 Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2765\" aria-describedby=\"caption-attachment-2765\" style=\"width: 256px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedron.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-2765\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tetrahedron.gif\" alt=\"It is a pyramid shape with a triangular base\" width=\"256\" height=\"256\" \/><\/a><figcaption id=\"caption-attachment-2765\" class=\"wp-caption-text\">Rotating animation of a tetrahedra<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> are categorized based on their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a> and structure. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are built around a molecular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a><\/strong>. A tetrahedron has a pyramid-like shape with four sides and four corners.\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> form the largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> on Earth, comprising the vast majority of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2586\">mantle<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a>. Of the nearly four thousand known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> on Earth, most are rare. There are only a few that make up most of the rocks likely to be encountered by surface dwelling creatures like us. These are generally called the <strong>rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a><\/strong>.<\/p>\n<figure id=\"attachment_2766\" aria-describedby=\"caption-attachment-2766\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.10_Tetrahedron.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2766\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.10_Tetrahedron-300x300-1.jpg\" alt=\"Model of silicon-oxygen tetrahedron of ping pong balls with a tiny silicon ion in the space in the middle of the four large balls\" width=\"300\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2766\" class=\"wp-caption-text\">Ping pong ball model of tetrahedron: balls are oxygen, lead sinker in center is silicon<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a> (SiO<sub>4<\/sub>) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. Each oxygen <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> has a -2 charge and the silicon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> has a +4 charge. The silicon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> shares one of its four valence electrons with each of the four oxygen ions in a covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> to create a symmetrical geometric four-sided pyramid figure. Only half of the oxygen\u2019s valence electrons are shared, giving the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a> an ionic charge of -4. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a> forms bonds with many other combinations of ions to form the large group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2767\" aria-describedby=\"caption-attachment-2767\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.11_Tetrahedron_open.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2767\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.11_Tetrahedron_open-300x255-1.jpg\" alt=\"Top ball removed showing the tiny silicon ion in the center\" width=\"300\" height=\"255\" \/><\/a><figcaption id=\"caption-attachment-2767\" class=\"wp-caption-text\">The silicon ion in the center of the tetrahedron<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The silicon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> is much smaller than the oxygen ions (see the figures) and fits into a small space in the center of the four large oxygen ions, seen if the top ball is removed (as shown in the figure to the right). <\/span><span style=\"font-weight: 400\">Because only one of the valence electrons of the corner oxygens is shared, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedron<\/a> has chemically active corners available to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a> or other positively charged ions such as Al<\/span><sub><span style=\"font-weight: 400\">+3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">+2,+3<\/span><\/sub><span style=\"font-weight: 400\">, Mg<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">, K<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, Na<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, and Ca<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">. Depending on many factors, such as the original <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a> chemistry, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica-oxygen tetrahedra<\/a> can combine with other tetrahedra in several different configurations. For example, tetrahedra can be isolated, attached in chains, sheets, or three dimensional structures. These combinations and others create the chemical structure in which positively charged ions can be inserted for unique chemical compositions forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> groups. \u00a0\u00a0<\/span><\/p>\n<h3><b>3.3.1 The dark ferromagnesian silicates<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2768\" aria-describedby=\"caption-attachment-2768\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.12_Peridot_in_basalt.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2768\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.12_Peridot_in_basalt-300x225-1.jpg\" alt=\"Many small crystall of the green mineral olivine in a mass of basalt\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-2768\" class=\"wp-caption-text\">Olivine crystals in basalt<\/figcaption><\/figure>\n<p><span style=\"font-size: 14pt\"><b>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">Olivine<\/a> Family<\/b><\/span><\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">Olivine<\/a> is the primary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> component in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2586\">mantle<\/a> rock such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2588\">peridotite<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1961\">basalt<\/a>. It is characteristically green when not weathered. The chemical formula is (Fe,Mg)<sub>2<\/sub>SiO<sub>4<\/sub>. As previously described, the comma between iron (Fe) and magnesium (Mg) indicates these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> occur in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a>.\u00a0<span style=\"font-weight: 400\">Not to be confused with a liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> occurs when two or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> have similar properties and can freely substitute for each other in the same location in the crystal structure.<\/span><\/p>\n<figure id=\"attachment_2769\" aria-describedby=\"caption-attachment-2769\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.13_Atomic_structure_of_olivine_1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-2769\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.13_Atomic_structure_of_olivine_1.png\" alt=\"Tetrahedral structure of olivine showing the independent tetrahedra connected together by anions of iron and\/or magnesium.\" width=\"300\" height=\"258\" \/><\/a><figcaption id=\"caption-attachment-2769\" class=\"wp-caption-text\">Tetrahedral structure of olivine<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">Olivine<\/a> is referred to as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> family because of the ability of iron and magnesium to substitute for each other. Iron and magnesium in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> family indicates a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> forming a compositional series within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> group which can form crystals of all iron as one end member and all mixtures of iron and magnesium in between to all magnesium at the other end member. Different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> names are applied to compositions between these end members.\u00a0 In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, the iron and magnesium ions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> are about the same size and charge, so either atom can fit into the same location in the growing crystals. Within the cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> crystals continue to grow until they solidify into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous rock<\/a>. The relative amounts of iron and magnesium in the parent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a> determine which <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> in the series form. Other rarer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> with similar properties to iron or magnesium, like manganese (Mn), can substitute into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> crystalline structure in small amounts. Such ionic substitutions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> crystals give rise to the great variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and are often responsible for differences in color and other properties within a group or family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">Olivine<\/a> has a pure iron end-member (called fayalite) and a pure magnesium end-member (called forsterite). Chemically, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> is mostly silicon, oxygen, iron, and magnesium and therefore is grouped among the dark-colored <\/span>ferromagnesian<span style=\"font-weight: 400\"> (iron=ferro, magnesium=magnesian) or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1956\">mafic<\/a><\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, a contraction of their chemical symbols Ma and Fe. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1956\">Mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are also referred to as dark-colored ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <em>Ferro<\/em> means iron and <em>magnesian<\/em> refers to magnesium. Ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> tend to be more dense than non-ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a>. This difference in density ends up being important in controlling the behavior of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> rocks that are built from these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>: whether a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2576\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2591\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2602\">subducts<\/a> or not is largely governed by the density of its rocks, which are in turn controlled by the density of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> that comprise them.<\/span><\/p>\n<p>The crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> is built from independent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals <\/a>with independent tetrahedral structures are called neosilicates (or orthosilicates). In addition to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a>, other common neosilicate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> include garnet, topaz, kyanite, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2175\">zircon<\/a>.<\/p>\n<p>Two other similar arrangements of tetrahedra are close in structure to the neosilicates and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2938\">grade<\/a> toward the next group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, the pyroxenes. In a variation on independent tetrahedra called sorosilicates, there are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> that share one oxygen between two tetrahedra, and include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> like pistachio-green epidote, a gemstone. Another variation are the cyclosilicates, which as the name suggests, consist of tetrahedral rings, and include gemstones such as beryl, emerald, aquamarine, and tourmaline<\/p>\n<h3><b>3.3.2 Pyroxene Family<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2770 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"300\" height=\"231\" \/><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2771\" aria-describedby=\"caption-attachment-2771\" style=\"width: 70px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Pyroxen-chain.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2771\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.15_Pyroxen-chain.png\" alt=\"Single chain of tetrahedra in pyroxene, alternating with adjacent corner oxygens bonded. The outer corners are active to bond with other anions.\" width=\"70\" height=\"517\" \/><\/a><figcaption id=\"caption-attachment-2771\" class=\"wp-caption-text\">Single chain tetrahedral structure in pyroxene<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">Pyroxene<\/a> is another family of dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, typically black or dark green in color. Members of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a> family have a complex chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a> that includes iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> to polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a>. <strong>Polymers<\/strong> are chains, sheets, or three-dimensional structures, and are formed by multiple tetrahedra covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> via their corner oxygen atoms. Pyroxenes are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1956\">mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> rocks such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2588\">peridotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1961\">basalt<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1964\">gabbro<\/a>, as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> rocks like eclogite and blue <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2929\">schist<\/a>.<\/p>\n<p>Pyroxenes are built from long, single chains of polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a> in which tetrahedra share two corner oxygens. The silica chains are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> together into the crystal structures by metal cations. A common member of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a> family is augite, itself containing several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> series with a complex chemical formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)<sub>2<\/sub>O<sub>6<\/sub> that gives rise to a number of individual <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> names.<\/p>\n<p>This single-chain crystalline structure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> with many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>, which can also freely substitute for each other. The generalized chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a> for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a> is XZ(Al,Si)<sub>2<\/sub>O<sub>6<\/sub>. X represents the ions Na, Ca, Mg, or Fe, and Z represents Mg, Fe, or Al. These ions have similar ionic sizes, which allows many possible substitutions among them. Although the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a> may freely substitute for each other in the crystal, they carry different ionic charges that must be balanced out in the final crystalline structure. For example Na has a charge of +1, but Ca has charge of +2. If a Na<sup>+<\/sup> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> substitutes for a Ca<sup>+2<\/sup> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a>, it creates an unequal charge that must be balanced by other ionic substitutions elsewhere in the crystal. Note that ionic size is more important than ionic charge for substitutions to occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> series in crystals.<\/p>\n<h3><\/h3>\n<h3><b>3.3.3 Amphibole Family<\/b><\/h3>\n<figure id=\"attachment_2773\" aria-describedby=\"caption-attachment-2773\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Orthoclase_Hornblende.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2773\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.15_Orthoclase_Hornblende-300x300-1.jpg\" alt=\"A crystal of orthoclase (potassium feldspar) wth elongated dark crystals of hornblende\" width=\"200\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-2773\" class=\"wp-caption-text\">Elongated crystals of hornblende in orthoclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2772\" aria-describedby=\"caption-attachment-2772\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.16_Amphibole.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2772\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.16_Amphibole-300x236-1.jpg\" alt=\"Black crystals of hornblende\" width=\"200\" height=\"157\" \/><\/a><figcaption id=\"caption-attachment-2772\" class=\"wp-caption-text\">Hornblende crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">Amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are built from polymerized double silica chains and they are also referred to as inosilicates. Imagine two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a> chains that connect together by sharing a third oxygen on each tetrahedra.\u00a0 Amphiboles are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> rocks and typically have a long-bladed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a><\/strong>. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a>, hornblende, is usually black; however, they come in a variety of colors depending on their chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2684\">metamorphic rock<\/a>, amphibolite, is primarily <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2774\" aria-describedby=\"caption-attachment-2774\" style=\"width: 79px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.17_Tremolite-chain.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2774\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.17_Tremolite-chain-79x300-1.png\" alt=\"Double chain structure of amphibole; two single chains laying together with the inner corners of each tetrahedron bonded and the outer cornera active to bond with anions\" width=\"79\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2774\" class=\"wp-caption-text\">Double chain structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Amphiboles are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a>. These dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1964\">gabbro<\/a>, baslt, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1963\">diorite<\/a>, and often form the black specks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1962\">granite<\/a>. Their chemical formula is very complex and generally written as (RSi<sub>4<\/sub>O<sub>11<\/sub>)<sub>2<\/sub>, where R represents many different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a>. For example, it can also be written more exactly as AX<sub>2<\/sub>Z<sub>5<\/sub>((Si,Al,Ti)<sub>8<\/sub>O<sub>22<\/sub>)(OH,F,Cl,O)<sub>2<\/sub>. In this formula A may be Ca, Na, K, Pb, or blank; X equals Li, Na, Mg, Fe, Mn, or Ca; and Z is Li, Na, Mg, Fe, Mn, Zn, Co, Ni, Al, \u00a0Cr, Mn, V, Ti, or Zr. The substitutions create a wide variety of colors such as green, black, colorless, white, yellow, blue, or brown. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">Amphibole<\/a> crystals can also include hydroxide ions (OH<sup>&#8211;<\/sup>)<sup>,<\/sup> which occurs from an interaction between the growing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and water <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolved<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a>.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><strong>3.3.4 Sheet Silicates<\/strong><\/h3>\n<figure id=\"attachment_2775\" aria-describedby=\"caption-attachment-2775\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2775\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany-300x225-1.jpg\" alt=\"Dark brown crystals of biotite mica showing sheet-like habit\" width=\"200\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-2775\" class=\"wp-caption-text\">Sheet crystals of biotite mica<\/figcaption><\/figure>\n<figure id=\"attachment_3637\" aria-describedby=\"caption-attachment-3637\" style=\"width: 250px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicaSheetUSGOV.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-166\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-300x226.jpg\" alt=\"Crystal of muscovite mica showing sheet structure of the mineral\" width=\"250\" height=\"188\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-300x226.jpg 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-65x49.jpg 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-225x169.jpg 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV-350x263.jpg 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/MicaSheetUSGOV.jpg 600w\" sizes=\"auto, (max-width: 250px) 100vw, 250px\" \/><\/a><figcaption id=\"caption-attachment-3637\" class=\"wp-caption-text\">Crystal of muscovite mica<\/figcaption><\/figure>\n<p>Sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> are built from tetrahedra which share all three of their bottom corner oxygens thus forming sheets of tetrahedra with their top corners available for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonding<\/a> with other atoms. Micas and clays are common types of sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a>, also known as phyllosilicates. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">Mica<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> rocks, while clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are more often found in sedimentary rocks. Two frequently found micas are dark-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">biotite<\/a>, frequently found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1962\">granite<\/a>, and light-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">muscovite<\/a>, found in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2684\">metamorphic rock<\/a> called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2929\">schist<\/a>.<\/p>\n<figure id=\"attachment_2777\" aria-describedby=\"caption-attachment-2777\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.20_Silicate-sheet-3D-polyhedra.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2777\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.20_Silicate-sheet-3D-polyhedra-300x197-1.png\" alt=\"Continuous sheets of tetradedra with all three base corners bonded to each other; the top corner active to bond with anions\" width=\"300\" height=\"197\" \/><\/a><figcaption id=\"caption-attachment-2777\" class=\"wp-caption-text\">Sheet structure of mica<\/figcaption><\/figure>\n<p>Chemically, sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> usually contain silicon and oxygen in a 2:5 ratio (Si<sub>4<\/sub>O<sub>10<\/sub>). Micas contain mostly silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">Biotite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica<\/a> has more iron and magnesium and is considered a ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">Muscovite<\/a> micas belong to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">Felsic<\/a> is a contraction formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>, the dominant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">felsic<\/a> rocks.<\/p>\n<figure id=\"attachment_2778\" aria-describedby=\"caption-attachment-2778\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.21_Crystal-structure-of-mica.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2778\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.21_Crystal-structure-of-mica-300x300-1.jpg\" alt=\"Diagram of mica crystal structure with the sheets of tetrahedra inverted onto each other into sandwiches with the active corners bonded with anions and the sandwiches connected together with large potassium ions that form weak bonds easily separated so the crystal comes apart into sheets.\" width=\"300\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2778\" class=\"wp-caption-text\">Crystal structure of a mica<\/figcaption><\/figure>\n<figure id=\"attachment_2779\" aria-describedby=\"caption-attachment-2779\" style=\"width: 296px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Illmenite-mica-sandwich.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2779\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Illmenite-mica-sandwich-296x300-1.jpg\" alt=\"Silica sheets layered in mica like bread and hjam in a stack of sandwiches\" width=\"296\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2779\" class=\"wp-caption-text\">Mica &#8220;silica sandwich&#8221; structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>The illustration of the crystalline structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica<\/a> shows the corner O atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with K, Al, Mg, Fe, and Si atoms, forming polymerized sheets of linked tetrahedra, with an octahedral layer of Fe, Mg, or Al, between them.\u00a0 The yellow potassium ions form Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> (attraction and repulsion between atoms, molecules, and surfaces) and hold the sheets together. Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> differ from\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Covalent_bond\">covalent<\/a>\u00a0and\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Ionic_bond\">ionic<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a>, and exist here between the sandwiches, holding them together into a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3213\">stack<\/a> of sandwiches. The Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> are weak compared to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> within the sheets, allowing the sandwiches to be separated along the potassium layers. This gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica<\/a> its characteristic property of easily cleaving into sheets.<\/p>\n<figure id=\"attachment_2780\" aria-describedby=\"caption-attachment-2780\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.22_Kaolinite-structure.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2780\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.22_Kaolinite-structure-300x244-1.jpg\" alt=\"Crystal structure of kaolinite, a clay mineral with sheet structure like mica except that the\" width=\"300\" height=\"244\" \/><\/a><figcaption id=\"caption-attachment-2780\" class=\"wp-caption-text\">Structure of kaolinite<\/figcaption><\/figure>\n<p>Clays <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2678\">sediments<\/a> formed by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2676\">weathering<\/a> of rocks and are another family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> with a tetrahedral sheet structure. Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> form a complex family, and are an important component of many sedimentary rocks. Other sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> include serpentine and chlorite, found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> rocks.<\/p>\n<p>Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of hydrous aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a>. One type of clay, kaolinite, has a structure like an open-faced sandwich, with the bread being a single layer of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedra<\/a> and a layer of aluminum as the spread in an octahedral configuration with the top oxygens of the sheets.<\/p>\n<h3><b>3.3.5 Framework Silicates<\/b><\/h3>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2829\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\" \/><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">Quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> are the two most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">continental crust<\/a>. In fact, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> itself is the single most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a>. There are two types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>, one containing potassium and abundant in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">felsic<\/a> rocks of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">continental crust<\/a>, and the other with sodium and calcium abundant in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1956\">mafic<\/a> rocks of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2581\">oceanic crust<\/a>.\u00a0 Together with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a>, these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are classified as framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a>. They are built with a three-dimensional framework of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica tetrahedra<\/a> in which all four corner oxygens are shared with adjacent tetrahedra. Within these frameworks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> are holes and spaces into which other ions like aluminum, potassium, sodium, and calcium can fit giving rise to a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> compositions and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2781\" aria-describedby=\"caption-attachment-2781\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/min-crust-pie-chart.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2781\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/min-crust-pie-chart-300x290-1.jpg\" alt=\"Feldspar is 51% of the chart.\" width=\"300\" height=\"290\" \/><\/a><figcaption id=\"caption-attachment-2781\" class=\"wp-caption-text\">Mineral abundance pie chart in Earth&#8217;s crust by Callan Bentley.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">Feldspars<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1962\">granite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1958\">rhyolite<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1961\">basalt<\/a> as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2914\">metamorphic<\/a> rocks and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3363\">detrital<\/a> sedimentary rocks. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3363\">Detrital<\/a> sedimentary rocks are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of mechanically weathered rock particles, like sand and gravel. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">Quartz<\/a> is especially abundant in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3363\">detrital<\/a> sedimentary rocks because it is very resistant to disintegration by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2676\">weathering<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a> is the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> on the Earth&#8217;s surface, due to its durability, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> in the Earth&#8217;s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a>, comprising roughly 50% of the total <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> that make up the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a>.<\/p>\n<figure id=\"attachment_2782\" aria-describedby=\"caption-attachment-2782\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.24_kspar280x210-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2782\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.24_kspar280x210-1-300x200-1.jpg\" alt=\"A group of crystals of pink potassium feldspar\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-2782\" class=\"wp-caption-text\">Pink orthoclase crystals<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">Quartz<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composed<\/a> of pure silica, SiO<sub>2<\/sub>, with the tetrahedra arranged in a three dimensional framework. Impurities consisting of atoms within this framework give rise to many varieties of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a> among which are gemstones like amethyst, rose <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a>, and citrine.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">Feldspars<\/a> are mostly silicon, oxygen, aluminum, potassium, sodium, and calcium. Orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> (KAlSi<sub>3<\/sub>O<sub>8<\/sub>), also called potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">K-spar<\/a>, is made of silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">Quartz<\/a> and orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1954\">Felsic<\/a> is the compositional term applied to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2675\">igneous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and rocks that contain an abundance of silica. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> with the formula (Ca,Na)AlSi<sub>3<\/sub>O<sub>8<\/sub>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> (Ca,Na) indicating a series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, one end of the series with calcium CaAl<sub>2<\/sub>Si<sub>2<\/sub>O<sub>8<\/sub>, called anorthite, and the other end with sodium NaAlSi<sub>3<\/sub>O<sub>8<\/sub>, called albite.\u00a0Note how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> accommodates the substitution of Ca<sup>++<\/sup> and Na<sup>+<\/sup>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> in this solid solution series have different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2783\" aria-describedby=\"caption-attachment-2783\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/23-feldspar-structure.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2783\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/23-feldspar-structure-300x271-1.gif\" alt=\"Framework structure of feldspar with all corners of tetrahedra shared with adjacent tetrahedra; there are holes in the structure in which large anions like potassium and sodium\/calcium fit\" width=\"300\" height=\"271\" \/><\/a><figcaption id=\"caption-attachment-2783\" class=\"wp-caption-text\">Crystal structure of feldspar<\/figcaption><\/figure>\n<p>Note that aluminum, which has a similar ionic size to silicon, can substitute for silicon inside the tetrahedra (see figure). Because potassium ions are so much larger than sodium and calcium ions, which are very similar in size, the inability of the crystal lattice to accommodate both potassium and sodium\/calcium gives rise to the two families of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>, orthoclase and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> respectively.\u00a0Framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> are called tectosilicates and include the alkali metal-rich feldspathoids and zeolites.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-19\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-19\" class=\"h5p-iframe\" data-content-id=\"19\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3752\" aria-describedby=\"caption-attachment-3752\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-175\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.3-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3752\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.3 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.4 Non-Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2784\" aria-describedby=\"caption-attachment-2784\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2784\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Hanksite-300x200-1.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-2784\" class=\"wp-caption-text\">Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few minerals that is considered a carbonate and a sulfate<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The crystal structure of non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> (see table) does not contain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silica-oxygen tetrahedra<\/a>. Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are economically important and provide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> resources such as copper, lead, and iron. They also include valuable non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> products such as salt, construction materials, and fertilizer.<\/p>\n<table>\n<tbody>\n<tr>\n<td><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Mineral<\/a> \u00a0Group<\/b><\/td>\n<td><b>Examples<\/b><\/td>\n<td><b>Formula<\/b><\/td>\n<td><b>Uses<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">Native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">gold, silver, copper<\/span><\/td>\n<td><span style=\"font-weight: 400\">Au, Ag, Cu<\/span><\/td>\n<td><span style=\"font-weight: 400\">Jewelry, coins, industry<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">Carbonates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, dolomite <\/span><\/td>\n<td><span style=\"font-weight: 400\">CaCO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, CaMg(CO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><\/td>\n<td><span style=\"font-weight: 400\">Lime, Portland cement<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">Oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">hematite, magnetite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3357\">bauxite<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">Fe<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">, a mixture of aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">Ores<\/a> of iron &amp; aluminum, pigments <\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1920\">Halides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a>, sylvite<\/span><\/td>\n<td><span style=\"font-weight: 400\">NaCl, KCl<\/span><\/td>\n<td><span style=\"font-weight: 400\">Table salt, fertilizer<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">Sulfides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">galena, chalcopyrite, cinnabar<\/span><\/td>\n<td><span style=\"font-weight: 400\">PbS, CuFeS<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">, HgS<\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">Ores<\/a> of lead, copper, mercury<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">Sulphates<\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a>, epsom salts<\/span><\/td>\n<td><span style=\"font-weight: 400\">CaSo<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b72H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O, MgSO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b77H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><\/td>\n<td><span style=\"font-weight: 400\">Sheetrock, therapeutic soak<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">Phosphates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">apatite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ca<\/span><sub><span style=\"font-weight: 400\">5<\/span><\/sub><span style=\"font-weight: 400\">(PO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">(F,Cl,OH) <\/span><\/td>\n<td><span style=\"font-weight: 400\">Fertilizer, teeth, bones<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em><span style=\"font-weight: 400\">Common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\"><em>silicate<\/em><\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\"><em>mineral<\/em><\/a> groups.<\/span><\/em><\/p>\n<h3><b>3.4.1 Carbonates<\/b><\/h3>\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2785\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"245\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb. Note the double-refracted word \u201ccalcite\u201d in the center of the figure due to birefringence.<\/figcaption><\/figure>\n<figure id=\"attachment_2786\" aria-describedby=\"caption-attachment-2786\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.29_Limestone_etched_section_KopeFm_new.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2786\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.29_Limestone_etched_section_KopeFm_new-281x300-1.jpg\" alt=\"Piece of limestone rock full of small fossils\" width=\"200\" height=\"214\" \/><\/a><figcaption id=\"caption-attachment-2786\" class=\"wp-caption-text\">Limestone with small fossils<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a>\u00a0(CaCO<sub>3<\/sub>) and dolomite (CaMg(CO<sub>3<\/sub>)<sub>2<\/sub>) are the two most frequently occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, and usually occur in sedimentary rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a> and dolostone rocks, respectively. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> rocks, such <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> and dolomite, are formed via evaporation and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitation<\/a>. However, most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a>-rich rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a>, are created by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2682\">lithification<\/a> of fossilized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2883\">marine<\/a> organisms. These organisms, including those we can see and many microscopic organisms, have shells or exoskeletons consisting of calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> (CaCO<sub>3<\/sub>). When these organisms die, their remains accumulate on the floor of the water body in which they live and the soft body parts decompose and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolve<\/a> away. The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> hard parts become included in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2678\">sediments<\/a>, eventually becoming the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2683\">sedimentary rock<\/a> called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a> may contain large, easy to see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2176\">fossils<\/a>, most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestones<\/a> contain the remains of microscopic creatures and thus originate from biological processes.<\/p>\n<figure id=\"attachment_2787\" aria-describedby=\"caption-attachment-2787\" style=\"width: 282px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bifringence.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2787\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Bifringence-282x300-1.jpg\" alt=\"Calcite crystal polarize light into two waves that vibrate at right angles to each other and pass through the crystal in different paths.\" width=\"282\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2787\" class=\"wp-caption-text\">Bifringence in calcite crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a> crystals show an interesting property called <strong>birefringence<\/strong>, meaning they polarize light into two wave components vibrating at right angles to each other. As the two light waves pass through the crystal, they travel at different velocities and are separated by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3091\">refraction<\/a> into two different travel paths. In other words, the crystal produces a double image of objects viewed through it. Because they polarize light, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> crystals are used in special petrographic microscopes for studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and rocks.<\/p>\n<p>Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are referred to as salts. The term <strong>salts<\/strong> used here refers to compounds made by replacing the hydrogen in natural acids. The most abundant natural acid is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2813\">carbonic acid<\/a> that forms by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a> of carbon dioxide in water. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">Carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are salts built around the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> (CO3<sup>-2<\/sup>) where calcium and\/or magnesium replace the hydrogen in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2813\">carbonic acid<\/a> (H<sub>2<\/sub>CO<sub>3<\/sub>). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a> and a closely related <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3362\">polymorph<\/a> aragonite are secreted by organisms to form shells and physical structures like corals. Many such creatures draw both calcium and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolved<\/a> bicarbonate ions (HCO<sub>3<\/sub><sup>&#8211;<\/sup>) in ocean water. As seen in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> identification section below, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> is easily <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2815\">dissolved<\/a> in acid and thus effervesces in dilute hydrochloric acid (HCl). Small dropper bottles of dilute hydrochloric acid are often carried by geologists in the field as well as used in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> identification labs.<\/p>\n<p>Other salts include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> (NaCl) in which sodium replaces the hydrogen in hydrochloric acid and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a> (Ca[SO<sub>4<\/sub>] \u2022 2 H<sub>2<\/sub>O) in which calcium replaces the hydrogen in sulfuric acid. Note that some water molecules are also included in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a> crystal. Salts are often formed by evaporation and are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2842\">evaporite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2788\" aria-describedby=\"caption-attachment-2788\" style=\"width: 425px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.30_Crystal_structure_of_Calcite.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2788\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.30_Crystal_structure_of_Calcite.png\" alt=\"Crystal structure of calcite showing the carbonate units of carbon surrounded by three oxygen ions and bonded to calcium ions.\" width=\"425\" height=\"520\" \/><\/a><figcaption id=\"caption-attachment-2788\" class=\"wp-caption-text\">Crystal structure of calcite<\/figcaption><\/figure>\n<p>The figure shows the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> (CaCO<sub>3<\/sub>). Like silicon, carbon has four valence electrons. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> unit consists of carbon atoms (tiny white dots) covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> to three oxygen atoms (red), one oxygen sharing two valence electrons with the carbon and the other two sharing one valence electron each with the carbon, thus creating triangular units with a charge of -2. The negatively charged <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> unit forms an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> with the Ca <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> (blue), which as a charge of +2.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><b>3.4.2 Oxides, Halides, and Sulfides<\/b><\/h3>\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2789\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"300\" height=\"256\" \/><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<p>After <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonates<\/a>, the next most common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1920\">halides<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfides<\/a>.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">Oxides<\/a> consist of metal ions covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with oxygen. The most familiar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> is rust, which is a combination of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a> (Fe<sub>2<\/sub>O<sub>3<\/sub>) and hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a>. Hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a> form when iron is exposed to oxygen and water. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a> are important for producing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> iron. When iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">ore<\/a> is smelted, it produces carbon dioxide (CO<sub>2<\/sub>) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> iron.<\/p>\n<p>The red color in rocks is usually due to the presence of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a>. For example, the red <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2834\">sandstone<\/a> cliffs in Zion National Park and throughout Southern Utah consist of white or colorless grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a> coated with iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> which serve as cementing agents holding the grains together.<\/p>\n<figure id=\"attachment_2790\" aria-describedby=\"caption-attachment-2790\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2790 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503-300x269-1.jpg\" alt=\"A red form of hematite called oolitic showing a mass of small round nodules\" width=\"300\" height=\"269\" \/><\/a><figcaption id=\"caption-attachment-2790\" class=\"wp-caption-text\">Oolitic hematite<\/figcaption><\/figure>\n<p>Other iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a> include limonite, magnetite, and hematite. Hematite occurs in many different crystal forms. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1933\">massive<\/a> form shows no external structure. Botryoidal hematite shows large concentric blobs. Specular hematite looks like a mass of shiny <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> crystals. Oolitic hematite looks like a mass of dull red fish eggs. These different forms of hematite are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2940\">polymorphs<\/a> and all have the same formula, Fe<sub>2<\/sub>O<sub>3<\/sub>.<\/p>\n<p>Other common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> include:<\/p>\n<ul>\n<li>ice (H<sub>2<\/sub>O), an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> of hydrogen<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3357\">bauxite<\/a> (Al<sub>2<\/sub>H<sub>2<\/sub>O<sub>4<\/sub>), hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a> of aluminum, an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">ore<\/a> for producing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> aluminum<\/li>\n<li>corundum (Al<sub>2<\/sub>O<sub>3<\/sub>), which includes ruby and sapphire gemstones.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2791\" aria-describedby=\"caption-attachment-2791\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.34_Halite-249324-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2791\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.34_Halite-249324-1-300x225-1.jpg\" alt=\"Crystals of halite showing cubic crystal habit\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-2791\" class=\"wp-caption-text\">Halite crystal showing cubic habit<\/figcaption><\/figure>\n<p>The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1920\">halides<\/a><\/strong> consist of halogens in column VII, usually fluorine or chlorine, ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> with sodium or other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a>. These include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> or sodium chloride (NaCl), common table salt; sylvite or potassium chloride (KCl); and fluorite or calcium fluoride (CaF<sub>2<\/sub>).<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2792\" aria-describedby=\"caption-attachment-2792\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2792\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level-300x220-1.jpg\" alt=\"Photo of salt crust at the Bonneville Salt Flats in Utah with mountains in the background.\" width=\"300\" height=\"220\" \/><\/a><figcaption id=\"caption-attachment-2792\" class=\"wp-caption-text\">Salt crystals at the Bonneville Salt Flats<\/figcaption><\/figure>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2793\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1920\">Halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> usually form from the evaporation of sea water or other isolated bodies of water. A well-known example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1920\">halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> deposits created by evaporation is the Bonneville Salt Flats, located west of the Great Salt Lake in Utah (see figure).<\/p>\n<p>&nbsp;<\/p>\n<p>Many important metal <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">ores<\/a> are <b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfides<\/a>, <\/b><span style=\"font-weight: 400\">in which metals are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> to sulfur.\u00a0<\/span><span style=\"font-weight: 400\">Significant examples include: \u00a0<\/span>galena<span style=\"font-weight: 400\"> (lead <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a>), <\/span>sphalerite<span style=\"font-weight: 400\"> (zinc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a>),<\/span> pyrite<\/p>\n<figure id=\"attachment_2794\" aria-describedby=\"caption-attachment-2794\" style=\"width: 175px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.37_pyrite1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2794\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.37_pyrite1-283x300-1.jpg\" alt=\"Cubic crystals of iron pyrite, called &quot;fools gold&quot;\" width=\"175\" height=\"185\" \/><\/a><figcaption id=\"caption-attachment-2794\" class=\"wp-caption-text\">Cubic crystals of pyrite<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">(<\/span><span style=\"font-weight: 400\">iron<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a>, sometimes called \u201cfool&#8217;s gold\u201d), and <\/span>chalcopyrite <span style=\"font-weight: 400\">(iron-copper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a>).<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">Sulfides<\/a> are well known for being important <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">ore<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. For example, galena is the main source of lead, sphalerite is the main source of zinc, and chalcopyrite is the main copper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3325\">ore<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3324\">mined<\/a> in porphyry deposits like the Bingham <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3324\">mine<\/a> (see <a href=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/chapter\/16-energy-and-mineral-resources\/\">chapter 16<\/a>). The largest sources of nickel, antimony, molybdenum, arsenic, and mercury are also <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfides<\/a>.<\/span><\/p>\n<h3><b>3.4.3 Sulfates<\/b><\/h3>\n<figure id=\"attachment_2795\" aria-describedby=\"caption-attachment-2795\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.39_SeleniteGypsumUSGOV.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2795\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.39_SeleniteGypsumUSGOV-300x284-1.jpg\" alt=\"A clear crystal of gypsum\" width=\"300\" height=\"284\" \/><\/a><figcaption id=\"caption-attachment-2795\" class=\"wp-caption-text\">Gypsum crystal<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">Sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> contain a metal <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a>, such as calcium, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonded<\/a> to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> is a combination of sulfur and oxygen (SO<sub>4<sup>&#8211;<\/sup><\/sub><sup>2<\/sup>). The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a> (CaSO<sub>4<\/sub>\u14272H<sub>2<\/sub>O) is used in construction materials such as plaster and drywall. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">Gypsum<\/a> is often formed from evaporating water and usually contains water molecules in its crystalline structure. The \u14272H<sub>2<\/sub>O in the formula indicates the water molecules are whole H<sub>2<\/sub>O. This is different from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a>, which contain a hydroxide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3371\">ion<\/a> (OH<sup>&#8211;<\/sup>) that is derived from water, but is missing a hydrogen ion (H<sup>+<\/sup>). The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1922\">sulfate<\/a> without water is a different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a> called anhydrite (CaSO<sub>4<\/sub>).<\/p>\n<h3><b>3.4.4 Phosphates<\/b><\/h3>\n<figure id=\"attachment_2796\" aria-describedby=\"caption-attachment-2796\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.40_Apatite_Canada.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2796\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.40_Apatite_Canada-236x300-1.jpg\" alt=\"A crystal of apatite\" width=\"150\" height=\"191\" \/><\/a><figcaption id=\"caption-attachment-2796\" class=\"wp-caption-text\">Apatite crystal<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">Phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> have a tetrahedral <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">phosphate<\/a> unit (PO<sub>4<\/sub><sup>-3<\/sup>) combined with various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2704\">anions<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2702\">cations<\/a>. In some cases arsenic or vanadium can substitute for phosphorus. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">Phosphates<\/a> are an important ingredient of fertilizers as well as detergents, paint, and other products. The best known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> is apatite, Ca<sub>5<\/sub>(PO<sub>4<\/sub>)<sub>3<\/sub>(F,Cl,OH), variations of which are found in teeth and bones. The gemstone turquoise [CuAl<sub>6<\/sub>(PO<sub>4<\/sub>)<sub>4<\/sub>(OH)<sub>8<\/sub>\u00b74H2O ] is a copper-rich <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1923\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> that, like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a>, contains water molecules.<\/span><\/p>\n<h3><b>3.4.5 Native Element Minerals<\/b><\/h3>\n<figure id=\"attachment_2798\" aria-describedby=\"caption-attachment-2798\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.43_Sulfer_Fumarola_Vulcano.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2798\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.43_Sulfer_Fumarola_Vulcano-300x225-1.jpg\" alt=\"Native sulfur deposited around the vent of a volcanic fumarole\" width=\"200\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-2798\" class=\"wp-caption-text\">Native sulfur deposited around a volcanic fumarole<\/figcaption><\/figure>\n<figure id=\"attachment_2797\" aria-describedby=\"caption-attachment-2797\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.41_Native_Copper-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2797\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.41_Native_Copper-1-300x284-1.jpg\" alt=\"Metallic native copper\" width=\"200\" height=\"189\" \/><\/a><figcaption id=\"caption-attachment-2797\" class=\"wp-caption-text\">Native copper<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">Native element minerals<\/a>, usually metals, occur in nature in a pure or nearly pure state. Gold is an example of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>; it is not very reactive and rarely <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> so it is usually found in an isolated or pure state. The non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> and poorly-reactive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> carbon is often found as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a>, such as graphite and diamonds. Mildly reactive metals like silver, copper, platinum, mercury, and sulfur sometimes occur as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">native element minerals<\/a>. Reactive metals such as iron, lead, and aluminum almost always <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> to other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> and are rarely found in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">native<\/a> state.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-20\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-20\" class=\"h5p-iframe\" data-content-id=\"20\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3751\" aria-describedby=\"caption-attachment-3751\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.4-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-191\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.4-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3751\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.4 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.5 Identifying Minerals<\/span><\/h2>\n<figure id=\"attachment_2799\" aria-describedby=\"caption-attachment-2799\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Curiosity_Mars_Rover_Finds_Mineral_Match.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2799\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Curiosity_Mars_Rover_Finds_Mineral_Match-300x268-1.jpg\" alt=\"The red rocks have a small hole drilled\" width=\"300\" height=\"268\" \/><\/a><figcaption id=\"caption-attachment-2799\" class=\"wp-caption-text\">The rover Curiosity drilled a hole in this rock from Mars, and confirmed the mineral Hematite, as mapped from satellites.<\/figcaption><\/figure>\n<p>Geologists identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> by their physical properties. In the field, where geologists may have limited access to advanced technology and powerful machines, they can still identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> by testing several physical properties: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a> and color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a>, cleavage and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a>, and some special properties. Only a few common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> make up the majority of Earth&#8217;s rocks and are usually seen as small grains in rocks. Of the several properties used for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, it is good to consider which will be most useful for identifying them in small grains surrounded by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/p>\n<h3><b>3.5.1 Luster and Color<\/b><\/h3>\n<figure id=\"attachment_2800\" aria-describedby=\"caption-attachment-2800\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Molly_Hill_molybdenite.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2800\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Molly_Hill_molybdenite-300x225-1.jpg\" alt=\"The crystal looks like metal.\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-2800\" class=\"wp-caption-text\">15 mm metallic hexagonal molybdenite crystal from Quebec.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The first thing to notice about a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> is its surface appearance, specifically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a> and color. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">Luster<\/a> describes how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> looks. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">Metallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a> looks like a shiny metal such as chrome, steel, silver, or gold. Submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a> has a duller appearance. Pewter, for example, shows submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a>.<\/p>\n<figure id=\"attachment_2801\" aria-describedby=\"caption-attachment-2801\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pewter-plate.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2801\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Pewter-plate-300x280-1.jpg\" alt=\"Antique pewter plate showing a more dull submetallic luster\" width=\"300\" height=\"280\" \/><\/a><figcaption id=\"caption-attachment-2801\" class=\"wp-caption-text\">Submetallic luster shown on an antique pewter plate.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3346\">Nonmetallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a> doesn\u2019t look like a metal and may be described as vitreous (glassy), earthy, silky, pearly, and other surface qualities. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3346\">Nonmetallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> may be shiny, although their vitreous shine is different from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a>. See the table for descriptions and examples of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3346\">nonmetallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a>.<\/p>\n<table style=\"width: 680px;height: 859px\">\n<tbody>\n<tr style=\"height: 32.625px\">\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">Luster<\/a><\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Image<\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Description<\/span><\/th>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Vitreous\/glassy<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3669\" aria-describedby=\"caption-attachment-3669\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.23_-Quartz_Bresil.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-195\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.23_-Quartz_Bresil-150x150.jpg\" alt=\"A mass of quartz crystals showing typical six sided habit with points\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-3669\" class=\"wp-caption-text\">Quartz crystals<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Surface is shiny like glass<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Earthy\/dull<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2802\" aria-describedby=\"caption-attachment-2802\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.47_earthy_luster_KaolinUSGOV-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-2802\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.47_earthy_luster_KaolinUSGOV-1-150x150-1.jpg\" alt=\"Specimen of kaolin, a clay oineral, showing dull or earthy luster\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-2802\" class=\"wp-caption-text\">Kaolin specimen showing dull or earthy luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Dull, like dried mud or clay<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Silky<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2803\" aria-describedby=\"caption-attachment-2803\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.48_silky_luster_Selenite_Gips_Marienglas-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2803\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.48_silky_luster_Selenite_Gips_Marienglas-1-300x230-1.jpg\" alt=\"Specimen showing silky luster\" width=\"150\" height=\"115\" \/><\/a><figcaption id=\"caption-attachment-2803\" class=\"wp-caption-text\">Specimen showing silky luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Soft shine like silk fabric<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Pearly<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2804\" aria-describedby=\"caption-attachment-2804\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.49_pearly_luster_Mineral_Mica_GDFL006.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2804\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.49_pearly_luster_Mineral_Mica_GDFL006-300x218-1.jpg\" alt=\"Specimen showing pearly luster like the inside of a clam shell\" width=\"150\" height=\"109\" \/><\/a><figcaption id=\"caption-attachment-2804\" class=\"wp-caption-text\">Specimen showing pearly luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Like the inside of a clam shell or mother-of-pearl<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Submetallic<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2805\" aria-describedby=\"caption-attachment-2805\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.44_submetallic_Sphalerite4.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2805\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.44_submetallic_Sphalerite4-300x277-1.jpg\" alt=\"Photo of mineral exhibiting submetallic luster\" width=\"150\" height=\"138\" \/><\/a><figcaption id=\"caption-attachment-2805\" class=\"wp-caption-text\">Submetallic luster on sphalerite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Has the appearance of dull metal,\u00a0like pewter. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> would usually still be considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a>. Submetallic appearance can occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> because of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2676\">weathering<\/a>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<figure id=\"attachment_2806\" aria-describedby=\"caption-attachment-2806\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Azurite_in_siltstone_Malbunka_mine_NT.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2806\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Azurite_in_siltstone_Malbunka_mine_NT-245x300-1.jpg\" alt=\"There are two dark blue disks on white siltstone.\" width=\"245\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2806\" class=\"wp-caption-text\">Azurite is ALWAYS a dark blue color, and has been used for centuries for blue pigment.<\/figcaption><\/figure>\n<p>Surface color may be helpful in identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, although it can be quite variable within the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> family. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Mineral<\/a> colors are affected by the main <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> as well as impurities in the crystals. These impurities may be rare <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>\u2014like manganese, titanium, chromium, or lithium\u2014even other molecules that are not normally part of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> formula. For example, the incorporation of water molecules gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a>, which is normally clear, a milky color.<\/p>\n<p>Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> predominantly show a single color. Malachite and azurite are green and blue, respectively, because of their copper content. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> have a predictable range of colors due to elemental substitutions, usually via a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">Feldspars<\/a>, the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> in the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a>, are complex, have <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2708\">solid solution<\/a> series, and present several colors including pink, white, green, gray and others. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> also come in several colors, influenced by trace amounts of several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>. The same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">element<\/a> may show up as different colors, in different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. With notable exceptions, color is usually not a definitive property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. For identifying many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. a more reliable indicator is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a>, which is the color of the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>.<\/p>\n<h3><b>3.5.2 Streak<\/b><\/h3>\n<figure id=\"attachment_2807\" aria-describedby=\"caption-attachment-2807\" style=\"width: 450px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2807\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-300x227-1.jpg\" alt=\"Pyrite showing a black streak on a white streak plate and rhodochrosite with a white streak on a black streak plate\" width=\"450\" height=\"341\" \/><\/a><figcaption id=\"caption-attachment-2807\" class=\"wp-caption-text\">Different minerals may have different streaks<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">Streak<\/a> examines the color of a powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>, and can be seen when a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> sample is scratched or scraped on an unglazed porcelain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2591\">plate<\/a>. A paper page in a field notebook may also be used for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> of some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> that are harder than the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2591\">plate<\/a> will not show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a>, but will scratch the porcelain. For these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> test can be obtained by powdering the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> with a hammer and smearing the powder across a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2591\">plate<\/a> or notebook paper.<\/p>\n<p>While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> surface colors and appearances may vary, their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> colors can be diagnostically useful. An example of this property is seen in the iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> hematite. Hematite occurs in a variety of forms, colors and lusters, from shiny <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> silver to earthy red-brown, and different physical appearances. A hematite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a> is consistently reddish brown, no matter what the original specimen looks like. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1921\">sulfide<\/a> or pyrite, is a brassy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> yellow. Commonly named fool\u2019s gold, pyrite has a characteristic black to greenish-black <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a>.<\/p>\n<h3><b>3.5.3 Hardness<\/b><\/h3>\n<figure id=\"attachment_2808\" aria-describedby=\"caption-attachment-2808\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.51_Mohs_Scale2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-2808\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.51_Mohs_Scale2-1024x714-1.jpg\" alt=\"Chart of Mohs Hardness Scale with minerals arranged in hardness from 1 to 10, also showing common items that correlate with the scale.\" width=\"1024\" height=\"714\" \/><\/a><figcaption id=\"caption-attachment-2808\" class=\"wp-caption-text\">Mohs Hardness Scale<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">Hardness<\/a> measures the ability of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> to scratch other substances. The Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">Hardness<\/a> Scale gives a number showing the relative scratch-resistance of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> when compared to a standardized set of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> of increasing hardness. The Mohs scale was developed by German geologist Fredrick Mohs in the early 20th century, although the idea of identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> goes back thousands of years. Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> values are determined by the strength of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>\u2019s atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a>.<\/p>\n<p>The figure shows the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> associated with specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> values, together with some common items readily available for use in field testing and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> identification. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> values run from 1 to 10, with 10 being the hardest; however, the scale is not linear. Diamond defines a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> of 10 and is actually about four times harder than corundum, which is 9. A steel pocketknife blade, which has a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a> value of 5.5, separates between hard and soft <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> on many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> identification keys.<\/p>\n<h3><b>3.5.4 Crystal Habit<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> can be identified by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a><\/strong>, how their crystals grow and appear in rocks. Crystal shapes are determined by the arrangement of the atoms within the crystal structure. For example, a cubic arrangement of atoms gives rise to a cubic-shaped <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> crystal. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">Crystal habit<\/a> refers to typically observed shapes and characteristics; however, they can be affected by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> crystallizing in the same rock. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are constrained so they do not develop their typical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a>, they are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1929\">anhedral<\/a><\/strong>. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1930\">Subhedral<\/a><\/strong> crystals are partially formed shapes. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1931\">euhedral<\/a><\/strong> crystal has a perfectly formed, unconstrained shape. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> crystallize in such tiny crystals, they do not show a specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a> to the naked eye. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, like pyrite, can have an array of different crystal habits, including cubic, dodecahedral, octahedral, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1933\">massive<\/a>. The table lists typical crystal habits of various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/p>\n<table style=\"width: 687px;height: 3774px\">\n<tbody>\n<tr>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">Habit<\/a><\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Image<\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Examples<\/span><\/strong><\/th>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Bladed<\/strong><\/p>\n<p>long and flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2809\" aria-describedby=\"caption-attachment-2809\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Kyanite_crystals.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2809\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Kyanite_crystals-300x225-1.jpg\" alt=\"The crystals are long and rectangular\" width=\"150\" height=\"113\" \/><\/a><figcaption id=\"caption-attachment-2809\" class=\"wp-caption-text\">Bladed kyanite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">kyanite,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2843\">gypsum<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Botryoidal\/mammillary<\/strong><\/p>\n<p>blobby, circular crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2810\" aria-describedby=\"caption-attachment-2810\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Malachite_Kolwezi_Katanga_Congo.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2810\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Malachite_Kolwezi_Katanga_Congo-300x174-1.jpg\" alt=\"The mineral is bulbous\" width=\"150\" height=\"87\" \/><\/a><figcaption id=\"caption-attachment-2810\" class=\"wp-caption-text\">Malachite from the Congo<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">hematite, malachite, smithsonite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Coating\/<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2860\">laminae<\/a>\/druse<\/strong><\/p>\n<p>crystals that are small and coat surfaces<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2811\" aria-describedby=\"caption-attachment-2811\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ametyst-geode.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2811\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ametyst-geode-300x200-1.jpg\" alt=\"The rock is hollowed and filled with purple minerals\" width=\"150\" height=\"100\" \/><\/a><figcaption id=\"caption-attachment-2811\" class=\"wp-caption-text\">Quartz (var. amethyst) geode<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, malachite, azurite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Cubic<\/strong><\/p>\n<p>cube-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2812\" aria-describedby=\"caption-attachment-2812\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.55_Cubic_Calcite-Galena-elm56c.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2812\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.55_Cubic_Calcite-Galena-elm56c-260x300-1.jpg\" alt=\"Cubic crystals of galena, a sulfide of lead\" width=\"150\" height=\"173\" \/><\/a><figcaption id=\"caption-attachment-2812\" class=\"wp-caption-text\">Cubic crystals of galena<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite, galena, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dodecahedral<\/strong><\/p>\n<p>12-sided polygon shapes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2813\" aria-describedby=\"caption-attachment-2813\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.53_habit_dodecahedral_Pyrite_elbe-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2813\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.53_habit_dodecahedral_Pyrite_elbe-300x195-1.jpg\" alt=\"Crystals of pyrite showing dodecahedral habit\" width=\"150\" height=\"97\" \/><\/a><figcaption id=\"caption-attachment-2813\" class=\"wp-caption-text\">Pyrite crystals with dodecahedral habit<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">garnet, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dendritic<\/strong><\/p>\n<p>branching crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2814\" aria-describedby=\"caption-attachment-2814\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dendrites01.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2814\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Dendrites01-300x203-1.jpg\" alt=\"The mineral look like a fern. They are black and branching.\" width=\"150\" height=\"101\" \/><\/a><figcaption id=\"caption-attachment-2814\" class=\"wp-caption-text\">Manganese dendrites, scale in mm.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">Mn-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxides<\/a>, copper, gold<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1932\">Equant<\/a><\/strong><\/p>\n<p>crystals that do not have a long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2815\" aria-describedby=\"caption-attachment-2815\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Peridot2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-209\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-272x300.jpg\" alt=\"The crystal is light green.\" width=\"150\" height=\"165\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-272x300.jpg 272w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-929x1024.jpg 929w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-768x847.jpg 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-65x72.jpg 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-225x248.jpg 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2-350x386.jpg 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Peridot2.jpg 1190w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-2815\" class=\"wp-caption-text\">Large olivine crystal<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a>, garnet, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Fibrous<\/strong><\/p>\n<p>thin, very long crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2816\" aria-describedby=\"caption-attachment-2816\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tremolite_Campolungo.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2816\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tremolite_Campolungo-300x186-1.jpg\" alt=\"It is white and fiberous\" width=\"150\" height=\"93\" \/><\/a><figcaption id=\"caption-attachment-2816\" class=\"wp-caption-text\">Tremolite, a type of amphibole<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">serpentine, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a>, zeolite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Layered, sheets<\/strong><\/p>\n<p>stacked, very thin, flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2817\" aria-describedby=\"caption-attachment-2817\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.18_Muscovite-Albite-122887.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2817\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.18_Muscovite-Albite-122887-300x254-1.jpg\" alt=\"Sheets of muscovite mica in crystal mass\" width=\"150\" height=\"127\" \/><\/a><figcaption id=\"caption-attachment-2817\" class=\"wp-caption-text\">Sheet crystals of muscovite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica <\/a>(<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">biotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">muscovite<\/a>, etc.)<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Lenticular\/platy<\/strong><\/p>\n<p>crystals that are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2591\">plate<\/a>-like<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2818\" aria-describedby=\"caption-attachment-2818\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-Wulfenite-tcw15b.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2818\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-Wulfenite-tcw15b-251x300-1.jpg\" alt=\"The orange wulfenite is bladed\" width=\"150\" height=\"179\" \/><\/a><figcaption id=\"caption-attachment-2818\" class=\"wp-caption-text\">Orange wulfenite on calcite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">selenite roses, wulfenite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Hexagonal<\/strong><\/p>\n<p>crystals with six sides<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3687\" aria-describedby=\"caption-attachment-3687\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-213 size-thumbnail\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Hanksite-1-150x150.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-3687\" class=\"wp-caption-text\">Hexagonal hanksite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a>, hanksite, corundum<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1933\">Massive<\/a>\/granular<\/strong><\/p>\n<p>Crystals with no obvious shape, microscopic crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2789\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"150\" height=\"128\" \/><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">limonite, pyrite, azurite, bornite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Octahedral<\/strong><\/p>\n<p>4-sided double pyramid crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2819\" aria-describedby=\"caption-attachment-2819\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2819\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90-300x182-1.jpg\" alt=\"Perfedt octahedral cleavage in fluorite generates octagon-shaped cleavage flakes.\" width=\"150\" height=\"91\" \/><\/a><figcaption id=\"caption-attachment-2819\" class=\"wp-caption-text\">Octagonal cleavage in fluorite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">diamond, fluorite, magnetite, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Prismatic\/columnar<\/strong><\/p>\n<p>very long, cylindrical crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2820\" aria-describedby=\"caption-attachment-2820\" style=\"width: 142px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tourmaline.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2820\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tourmaline-142x300-1.jpg\" alt=\"The mineral is a long cylinder.\" width=\"142\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2820\" class=\"wp-caption-text\">Columnar tourmaline<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">tourmaline, beryl, barite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Radiating<\/strong><\/p>\n<p>crystals that grow from a point and fan out<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2821\" aria-describedby=\"caption-attachment-2821\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pyrophyllite-236595.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2821\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Pyrophyllite-236595-217x300-1.jpg\" alt=\"The mineral is orange\" width=\"150\" height=\"207\" \/><\/a><figcaption id=\"caption-attachment-2821\" class=\"wp-caption-text\">Pyrophyllite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite &#8220;suns&#8221;, pyrophyllite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Rhombohedral<\/strong><\/p>\n<p>crystals shaped like slanted cubes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2785\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"150\" height=\"183\" \/><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, dolomite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tabular\/blocky\/stubby<\/strong><\/p>\n<p>sharp-sided crystals with no long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2770\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"150\" height=\"116\" \/><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tetrahedral<\/strong><\/p>\n<p>three-sided, pyramid-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2822\" aria-describedby=\"caption-attachment-2822\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2822\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Tetrahedrite-Chalcopyrite-Sphalerite-251531-300x218-1.jpg\" alt=\"The dark brown mineral is triangular\" width=\"150\" height=\"109\" \/><\/a><figcaption id=\"caption-attachment-2822\" class=\"wp-caption-text\">Tetrahedrite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">magnetite, spinel, tetrahedrite<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2824\" aria-describedby=\"caption-attachment-2824\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/GypsumStriations.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2824\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/GypsumStriations-251x300-1.jpg\" alt=\"The mineral has many parallel lines on it\" width=\"150\" height=\"179\" \/><\/a><figcaption id=\"caption-attachment-2824\" class=\"wp-caption-text\">Gypsum with striations<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2823\" aria-describedby=\"caption-attachment-2823\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Staurolite-62645.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2823\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Staurolite-62645-279x300-1.jpg\" alt=\"The brown minerals are replicated in different directions\" width=\"150\" height=\"161\" \/><\/a><figcaption id=\"caption-attachment-2823\" class=\"wp-caption-text\">Twinned staurolite<\/figcaption><\/figure>\n<p>Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a> that may be used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> is striations, which are dark and light parallel lines on a crystal face. Twinning is another, which occurs when the crystal structure replicates in mirror images along certain directions in the crystal.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2825\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\" \/><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Striations on plagioclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Striations and twinning are related properties in some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>. Striations are optical lines on a cleavage surface. Because of twinning in the crystal, striations show up on one of the two cleavage faces of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> crystal.<\/p>\n<h3><b>3.5.5 Cleavage and Fracture<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> often show characteristic patterns of breaking along specific cleavage planes or show characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a> patterns. Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as reflective surfaces on the crystal, as parallel cracks that penetrate into the crystal, or show on the edge or side of the crystal as a series of steps like rice <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3162\">terraces<\/a>. Cleavage arises in crystals where the atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> between atomic layers are weaker along some directions than others, meaning they will break preferentially along these planes.\u00a0Because they develop on atomic surfaces in the crystal, cleavage planes are optically smooth and reflect light, although the actual break on the crystal may appear jagged or uneven. In such cleavages, the cleavage surface may appear like rice <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3162\">terraces<\/a> on a mountainside that all reflect sunlight from a particular sun angle. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> have a strong cleavage, some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> only have weak cleavage or do not typically demonstrate cleavage.<\/p>\n<figure id=\"attachment_2826\" aria-describedby=\"caption-attachment-2826\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.57_conchoidal_Citrine-sample2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2826\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.57_conchoidal_Citrine-sample2-300x225-1.jpg\" alt=\"A specimen of a variety of quartz showing conchoidal fracture\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-2826\" class=\"wp-caption-text\">Citrine, a variety of quartz showing conchoidal fracture<\/figcaption><\/figure>\n<p>For example, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">olivine<\/a> rarely show cleavage and typically break into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1935\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a> patterns.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2827\" aria-describedby=\"caption-attachment-2827\" style=\"width: 452px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/cryview_graphite_v1.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2827 size-full\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/cryview_graphite_v1.gif\" alt=\"Structure of graphite, showing single carbon layers with weak bonds holding them together\" width=\"452\" height=\"504\" \/><\/a><figcaption id=\"caption-attachment-2827\" class=\"wp-caption-text\">Graphite showing layers of carbon atoms separated by a gap with weak bonds holding the layers together.<\/figcaption><\/figure>\n<p>Graphite has its carbon atoms arranged into layers with relatively strong <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> within the layer and very weak <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> between the layers.\u00a0 Thus graphite cleaves readily between the layers and the layers slide easily over one another giving graphite its lubricating quality.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a> surfaces may be rough and uneven or they may be show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1935\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a>. Uneven <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a> patterns are described as irregular, splintery, fibrous. A conchoidal fracture has a smooth, curved surface like a shallow bowl or conch shell, often with curved ridges. Natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1181\">volcanic<\/a> glass, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1947\">obsidian<\/a>, breaks with this characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1935\">conchoidal<\/a> pattern<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2828\" aria-describedby=\"caption-attachment-2828\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.64_galena_cleavage_Argentiferous_Galena-458851.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2828 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.64_galena_cleavage_Argentiferous_Galena-458851-300x261-1.jpg\" alt=\"Specimen of galena showing cubic cleavage\" width=\"300\" height=\"261\" \/><\/a><figcaption id=\"caption-attachment-2828\" class=\"wp-caption-text\">Cubic cleavage of galena; note how the cleavage surfaces show up as different but parallel layers in the crystal.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>To work with cleavage, it is important to remember that cleavage is a result of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a> separating along planes of atoms in the crystal structure. On some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, <strong>cleavage planes<\/strong> may be confused with crystal faces. This will usually not be an issue for crystals of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> that grew together within rocks. The act of breaking the rock to expose a fresh face will most likely break the crystals along cleavage planes. Some cleavage planes are parallel with crystal faces but many are not.\u00a0Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as parallel cracks that penetrate into the crystal (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a> below), or show on the edge or side of the crystal as a series of steps like rice <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3162\">terraces<\/a>. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">quartz<\/a> below).<\/p>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2829\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\" \/><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, distinguishing cleavage planes from crystal faces may be challenging for the student. Understanding the nature of cleavage and referring to the number of cleavage planes and cleavage angles on identification keys should provide the student with enough information to distinguish cleavages from crystal faces. Cleavage planes may show as multiple parallel cracks or flat surfaces on the crystal. Cleavage planes may be expressed as a series of steps like terraced rice paddies. See the cleavage surfaces on galena above or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> below. Cleavage planes arise from the tendency of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> crystals to break along specific planes of weakness within the crystal favored by atomic arrangements. The number of cleavage planes, the quality of the cleavage surfaces, and the angles between them are diagnostic for many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and cleavage is one of the most useful properties for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>. Learning to recognize cleavage is an especially important and useful skill in studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>.<\/span><\/p>\n<figure id=\"attachment_2830\" aria-describedby=\"caption-attachment-2830\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.61_Cleavage_steps_in_wollastonite.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2830\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.61_Cleavage_steps_in_wollastonite-300x224-1.jpg\" alt=\"Image of wollastonite, a crystal showing step-like cleavage on one side. All steps are along the same direction of cleavage.\" width=\"300\" height=\"224\" \/><\/a><figcaption id=\"caption-attachment-2830\" class=\"wp-caption-text\">Steps of cleavage along the same cleavage direction<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2831\" aria-describedby=\"caption-attachment-2831\" style=\"width: 220px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.63_cleavage_in_Amphibole.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2831\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.63_cleavage_in_Amphibole-295x300-1.jpg\" alt=\"Photomicrograph showing 120\/60 degree cleavage in amphibole\" width=\"220\" height=\"224\" \/><\/a><figcaption id=\"caption-attachment-2831\" class=\"wp-caption-text\">Photomicrograph showing 120\/60 degree cleavage within a grain of amphibole<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>As an identification property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, cleavage is usually given in terms of the quality of the cleavage (perfect, imperfect, or none), the number of cleavage surfaces, and the angles between the surfaces.\u00a0The most common number of cleavage plane directions in the common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are: one perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica<\/a>), two cleavage planes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">pyroxene<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">amphibole<\/a>), and three cleavage planes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>, and galena). One perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">mica<\/a>) develops on the top and bottom of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> specimen with many parallel cracks showing on the sides but no angle of intersection. Two cleavage planes intersect at an angle. Common cleavage angles are 60\u00b0, 75\u00b0, 90\u00b0, and 120\u00b0.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">Amphibole<\/a> has two cleavage planes at\u00a060\u00b0 and\u00a0120\u00b0. Galena and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> have three cleavage planes at 90\u00b0 (cubic cleavage). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a> cleaves readily in three directions producing a cleavage figure called a rhomb that looks like a cube squashed over toward one corner giving rise to the approximately 75\u00b0 cleavage angles. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">Pyroxene<\/a> has an imperfect cleavage with two planes at 90\u00b0.<\/p>\n<p><strong>Cleavages on common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a><\/strong><\/p>\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1915\">Quartz<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1935\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2711\">Olivine<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1935\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1914\">Mica<\/a>\u20141 perfect<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">Feldspar<\/a>\u20142 perfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2712\">Pyroxene<\/a>\u20142 imperfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2713\">Amphibole<\/a>\u20142 perfect at 60\u00b0\/120\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">Calcite<\/a>\u20143 perfect at approximately 75\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">Halite<\/a>, galena, pyrite\u20143 perfect at 90\u00b0<\/li>\n<\/ul>\n<h3><b>3.5.6 Special Properties <\/b><\/h3>\n<figure id=\"attachment_2832\" aria-describedby=\"caption-attachment-2832\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ulexit_Fernsehstein.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-2832\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ulexit_Fernsehstein-150x150-1.jpg\" alt=\"The words on the page are projected upwards onto the mineral\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-2832\" class=\"wp-caption-text\">A demonstration of ulexite&#8217;s image projection<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Special properties are unique and identifiable characteristics used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> or that allow some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> to be used for special purposes.\u00a0<\/span>Ulexite has a fiber-optic property that can project images through the crystal like a high-definition television screen (see figure). A simple identifying special property is taste, such as the salty flavor of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2844\">halite<\/a> or common table salt (NaCl). Sylvite is potassium chloride (KCl) and has a more bitter taste.<\/p>\n<figure id=\"attachment_2833\" aria-describedby=\"caption-attachment-2833\" style=\"width: 225px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Latrobe_gold_nugget_Natural_History_Museum.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2833\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Latrobe_gold_nugget_Natural_History_Museum-225x300-1.jpg\" alt=\"The nugget is gold\" width=\"225\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2833\" class=\"wp-caption-text\">Native gold has one of the highest specific gravities.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Another property geologists may use to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> is a property related to density called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">specific gravity<\/a><\/strong>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">Specific gravity<\/a> measures the weight of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> specimen relative to the weight of an equal volume of water. The value is expressed as a ratio between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> and water weights. To measure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">specific gravity<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> specimen is first weighed in grams then submerged in a graduated cylinder filled with pure water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a>. The rise in water level is noted using the cylinder\u2019s graduated scale. Since the weight of water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2689\">temperature<\/a> is 1 gram per cubic centimeter, the ratio of the two weight numbers gives the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">specific gravity<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">Specific gravity<\/a> is easy to measure in the laboratory but is less useful for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> identification in the field than other more easily observed properties, except in a few rare cases such as the very dense galena or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1924\">native<\/a> gold. The high density of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> gives rise to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2647\">qualitative<\/a> property called \u201cheft.\u201d Experienced geologists can roughly assess <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1937\">specific gravity<\/a> by heft, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2645\">subjective<\/a> quality of how heavy the specimen feels in one\u2019s hand relative to its size.<\/p>\n<p>A simple test for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> and dolomite is to drop a bit of dilute hydrochloric acid (10-15% HCl) on the specimen. If the acid drop effervesces or fizzes on the surface of the rock, the specimen is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a>. If it does not, the specimen is scratched to produce a small amount of powder and test with acid again. If the acid drop fizzes slowly on the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a>, the specimen is dolomite. The difference between these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> can be seen in the video. Geologists who work with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1917\">carbonate<\/a> rocks carry a small dropper bottle of dilute HCl in their field kit. Vinegar, which contains acetic acid, can be used for this test and is used to distinguish non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1918\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2176\">fossils<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2851\">limestone<\/a>. While acidic, vinegar produces less of a fizzing reaction because acetic acid is a weaker acid.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Calcite and Dolomite Reacting with Hydrochloric Acid\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/DX6ZMPbA09U?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<figure id=\"attachment_3750\" aria-describedby=\"caption-attachment-3750\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-and-Dolomite-YouTube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-228\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Calcite-and-Dolomite-YouTube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3750\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<figure id=\"attachment_2834\" aria-describedby=\"caption-attachment-2834\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Magnetite_Lodestone.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2834\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Magnetite_Lodestone-300x200-1.jpg\" alt=\"The paperclip is sticking up into the air.\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-2834\" class=\"wp-caption-text\">Paperclips attach to lodestone (magnetite).<\/figcaption><\/figure>\n<p>Some iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are magnetic and are attracted to magnets. A common name for a naturally magnetic iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1919\">oxide<\/a> is <strong>lodestone<\/strong>. Others include magnetite (Fe3O<sub>4<\/sub>) and ilmenite (FeTiO<sub>3<\/sub>). Magnetite is strongly attracted to magnets and can be magnetized. Ilmenite and some types of hematite are weakly magnetic.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2825 size-medium\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\" \/><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Iridescence on plagioclase; also showing striations on the cleavage surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> and mineraloids scatter light via a phenomenon called <strong>iridescence<\/strong>. This property occurs in labradorite (a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a>) and opal. It is also seen in biologically created substances like pearls and seashells. Cut diamonds show iridescence and the jeweler\u2019s diamond cut is designed to maximize this property.<\/span><\/p>\n<figure id=\"attachment_2835\" aria-describedby=\"caption-attachment-2835\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2835\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD-300x217-1.jpg\" alt=\"Image showing exsolution lamellae in potassium feldspar. These are separations of sodium feldspar from potassium feldspar within the crystal, not striations.\" width=\"300\" height=\"217\" \/><\/a><figcaption id=\"caption-attachment-2835\" class=\"wp-caption-text\">Exsolution lamellae within potassium feldspar<\/figcaption><\/figure>\n<p><strong>Striations<\/strong> on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> cleavage faces are an optical property that can be used to separate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> from potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">K-spar<\/a>). A process called twinning creates parallel zones in the crystal that are repeating mirror images. The actual cleavage angle in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a> is slightly different than 90<sup>o<\/sup> and the alternating mirror images in these twinned zones produce a series of parallel lines on one of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">plagioclase<\/a>\u2019s two cleavage faces. Light reflects off these twinned lines at slightly different angles which then appear as light and dark lines called striations on the cleavage surface.\u00a0Potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> does not exhibit twinning or striations but may show linear features called <strong>exsolution lamellae<\/strong>, also known as perthitic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2925\">lineation<\/a> or simply perthite. Because sodium and potassium do not fit into the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> crystal structure, the lines are created by small amounts of sodium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> (albite) separating from the dominant potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">K-spar<\/a>) within the crystal structure. The two different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1916\">feldspars<\/a> crystallize out into roughly parallel zones within the crystal, which are seen as these linear markings.<\/p>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-2793\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p>One of the most interesting special <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> properties is <strong>fluorescence<\/strong>. Certain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a>, or \u00a0trace <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a> within them, give off visible light when exposed to ultraviolet radiation or black light. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">mineral<\/a> exhibits have a fluorescence room equipped with black lights so this property can be observed. An even rarer optical property is phosphorescence. <strong>Phosphorescent<\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> absorb light and then slowly release it, much like a glow-in-the-dark sticker.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-21\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-21\" class=\"h5p-iframe\" data-content-id=\"21\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.5 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3749\" aria-describedby=\"caption-attachment-3749\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.5-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-231\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/3.5-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3749\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.5 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 18pt\"><strong>Summary<\/strong><\/span><\/h2>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> are the building blocks of rocks and essential to understanding geology. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Mineral<\/a> properties are determined by their atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bonds<\/a>. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> begin in a fluid, and either crystallize out of cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2672\">magma<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2707\">precipitate<\/a> as ions and molecules out of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2706\">saturated<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2705\">solution<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> are largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> on Earth, by number of varieties and relative quantity, making up a large portion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">crust<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2586\">mantle<\/a>. Based on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2710\">silicon-oxygen tetrahedra<\/a>, the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicates<\/a> reflects the fact that silicon and oxygen are the top two of Earth\u2019s most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2700\">elements<\/a>. Non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2709\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">minerals<\/a> are also economically important, and providing many types of construction and manufacturing materials. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2687\">Minerals<\/a> are identified by their unique physical properties, including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1925\">luster<\/a>, color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1926\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1927\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1928\">crystal habit<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_1934\">fracture<\/a>, cleavage, and special properties.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-22\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-22\" class=\"h5p-iframe\" data-content-id=\"22\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 3 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3748\" aria-describedby=\"caption-attachment-3748\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ch.3-Review-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-232\" src=\"https:\/\/pressbooks.ccconline.org\/accdigitalmarketing\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-150x150.png 150w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-300x300.png 300w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-1024x1024.png 1024w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-768x768.png 768w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-65x65.png 65w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-225x225.png 225w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code-350x350.png 350w, https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-content\/uploads\/sites\/222\/2025\/01\/Ch.3-Review-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-3748\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 3 via this QR Code.<\/figcaption><\/figure>\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Clarke, F.W.H.S.W., 1927, The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">Composition<\/a> of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2580\">Crust<\/a>: Professional Paper, United States Geological Survey, Professional Paper.<\/li>\n<li class=\"csl-entry\">Gordon, L.M., and Joester, D., 2011, Nanoscale chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3096\">tomography<\/a> of buried organic-inorganic interfaces in the chiton tooth: Nature, v. 469, no. 7329, p. 194\u2013197.<\/li>\n<li class=\"csl-entry\">Hans Wedepohl, K., 1995, The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2831\">composition<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2575\">continental crust<\/a>: Geochim. Cosmochim. Acta, v. 59, no. 7, p. 1217\u20131232.<\/li>\n<li class=\"csl-entry\">Lambeck, K., 1986, Planetary evolution: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2848\">banded iron<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2960\">formations<\/a>: v. 320, no. 6063, p. 574\u2013574.<\/li>\n<li class=\"csl-entry\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_3345\">metallic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_233_2703\">bond<\/a> | chemistry.<\/li>\n<li class=\"csl-entry\">Scerri, E.R., 2007, The Periodic Table: Its Story and Its Significance: Oxford University Press, USA.<\/li>\n<li class=\"csl-entry\">Thomson, J.J., 1897, XL. Cathode Rays: Philosophical Magazine Series 5, v. 44, no. 269, p. 293\u2013316.<\/li>\n<li class=\"csl-entry\">Trenn, T.J., Geiger, H., Marsden, E., and Rutherford, E., 1974, The Geiger-Marsden Scattering Results and Rutherford\u2019s Atom, July 1912 to July 1913: The Shifting Significance of Scientific Evidence: Isis, v. 65, no. 1, p. 74\u201382.<\/li>\n<\/ol>\n<\/div>\n<p><span style=\"font-weight: 400\">\u00a0<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_233_2687\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2687\"><div tabindex=\"-1\"><p>A natural substance that is typically solid, has a crystalline structure, and is typically formed by inorganic processes. Minerals are the building blocks of most rocks.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2700\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2700\"><div tabindex=\"-1\"><p>A group of all atoms with a specific number of protons, having specific, universal, and unique properties.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2703\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2703\"><div tabindex=\"-1\"><p>Two or more atoms or ions that are connected chemically.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2710\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2710\"><div tabindex=\"-1\"><p>A anion structure of one silicon bonded to four oxygens, in the shape of a tetrahedron, with the silicon in the center and four oxygens at the corners of the structure. It has a net charge of -4, and can bond to cations to form silicate minerals.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2709\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2709\"><div tabindex=\"-1\"><p>Mineral group in which the silica tetrahedra, SiO4-4, is the building block.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1919\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1919\"><div tabindex=\"-1\"><p>Minerals in which ions are bonded to oxygen, such as in ice, H2O.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1921\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1921\"><div tabindex=\"-1\"><p>Minerals bonded via a sulfur (S-2) atom.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1922\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1922\"><div tabindex=\"-1\"><p>Minerals bonded via a sulfate ion, SO4-2.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1917\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1917\"><div tabindex=\"-1\"><p>Mineral group in which the carbonate ion, CO3-2, is the building block. This can also refer to the rocks that are made from these minerals, namely limestone and dolomite (dolostone).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2689\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2689\"><div tabindex=\"-1\"><p>The measure of the vibrational (kinetic) energy of a substance.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2831\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2831\"><div tabindex=\"-1\"><p>The mineral make up of a rock, i.e. which minerals are found within a rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1918\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1918\"><div tabindex=\"-1\"><p>CaCO3. Pure form is clear, but can take on many different colors with impurities. It is soft, fizzes in acid, and has three cleavages that are not at 90\u00b0. Thus, it can form slanted blocks, though it is visually common to be without any structure. Found in many sedimentary rocks from marine settings, rarely in igneous rocks, in the metamorphic rock marble, but is common as a secondary mineral throughout surface rocks.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2827\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2827\"><div tabindex=\"-1\"><p>Changes in sedimentary rocks due to increased (but low when compared to metamorphism) temperatures and pressures. This can include deposition of new minerals (e.g. limestone converting to dolomite) or dissolution of existing minerals.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2856\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2856\"><div tabindex=\"-1\"><p>Former swamp-derived (plant) material that is part of the rock record.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1947\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1947\"><div tabindex=\"-1\"><p>Dark colored volcanic glass, with extremely small microscopic crystals or no crystals. Typically form from felsic volcanism.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2675\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2675\"><div tabindex=\"-1\"><p>Rocks that are formed from liquid rock, i.e. from volcanic processes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1204\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1204\"><div tabindex=\"-1\"><p>The physical breakdown (weathering) of bedrock by processes such as pressure, ice expansion, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2812\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2812\"><div tabindex=\"-1\"><p>Breaking down of mineral material via chemical methods, like dissolution and oxidation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2707\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2707\"><div tabindex=\"-1\"><p>The act of a solid coming out of solution, typically resulting from a drop in temperature or a decrease of the dissolving material.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2705\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2705\"><div tabindex=\"-1\"><p>The act of taking a solid and dissolving it into a liquid. This commonly occurs with salts and other minerals in water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2914\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2914\"><div tabindex=\"-1\"><p>Rocks and minerals that change within the Earth are called metamorphic, changed by heat and pressure. Metamorphism is the name of the process.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2701\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2701\"><div tabindex=\"-1\"><p>An atom that has different number of neutrons but the same number of protons. While most properties are based on the number of protons in an element, isotopes can have subtle changes between them, including temperature fractionation and radioactivity.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2575\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2575\"><div tabindex=\"-1\"><p>The layers of igneous, sedimentary, and metamorphic rocks that form the continents. Continental crust is much thicker than oceanic crust. Continental crust is defined as having higher concentrations of&nbsp;very light elements like K, Na, and Ca, and is the lowest density rocky layer of Earth. Its average composition is similar to granite.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3371\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3371\"><div tabindex=\"-1\"><p>An atom or molecule that has a charge (positive or negative) due to the loss or gain of electrons.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2711\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2711\"><div tabindex=\"-1\"><p>(Fe,Mg)2SiO4.&nbsp;Typically translucent olive green and equant, with no cleavage. Common in mafic igneous rocks and in the mantle, but easily weathered in surface conditions. Structure is isolated silica tetrahedra. Known as peridot when a gem.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3361\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3361\"><div tabindex=\"-1\"><p>A rule that says the outer valence shell of electrons is complete when it contains 8 electrons.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2702\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2702\"><div tabindex=\"-1\"><p>A positively-charged ion. In geology, this commonly includes ions of the elements Ca+2, Na+1, K+1, Fe+2,+3, Al+3, and Mg+2.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2704\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2704\"><div tabindex=\"-1\"><p>A negatively-charged ion. In geology, this commonly includes elements and molecules like SiO4-4, S-2, SO4-4, and O-2.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2818\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2818\"><div tabindex=\"-1\"><p>Certain metallic elements (like iron) take in oxygen, causing reactions like rust.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2844\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2844\"><div tabindex=\"-1\"><p>Also known as rock salt, or table salt. 3 cleavages at 90\u00b0, cubic crystal habit. Typically clear or white, hardness of 3.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2674\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2674\"><div tabindex=\"-1\"><p>The process of liquid rock freezing into solid rock. Because liquid rock is made of many components, the process is complex as different components freeze at different temperatures.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2672\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2672\"><div tabindex=\"-1\"><p>Liquid rock within the Earth.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2815\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2815\"><div tabindex=\"-1\"><p>The process in which solids (like minerals) are disassociated and the ionic components are dispersed in a liquid (usually water).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2706\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2706\"><div tabindex=\"-1\"><p>A solution that has the maximum allowed dissolved component, and is unable to dissolve more.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3119\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3119\"><div tabindex=\"-1\"><p>Detached, free-falling rocks from very steep slopes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2678\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2678\"><div tabindex=\"-1\"><p>Pieces of rock that have been weathered and possibly eroded.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2846\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2846\"><div tabindex=\"-1\"><p>Porous variety of carbonate that form in relatively unheated water, sometimes as towers and spires.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1700\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1700\"><div tabindex=\"-1\"><p>A period of cooler temperatures on Earth in which ice sheets can grow on continents.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2847\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2847\"><div tabindex=\"-1\"><p>Porous, concentric, or layered variety of carbonate that forms with often heated water in springs and\/or caves.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3162\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3162\"><div tabindex=\"-1\"><p>An elevated erosional surface caused by glacial or fluvial action.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3174\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3174\"><div tabindex=\"-1\"><p>A place where pressurized groundwater flows onto the surface.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3134\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3134\"><div tabindex=\"-1\"><p>A channelled body of water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2673\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2673\"><div tabindex=\"-1\"><p>Liquid rock on the surface of the Earth.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3362\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3362\"><div tabindex=\"-1\"><p>Minerals with the same composition and different crystal structures<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2883\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2883\"><div tabindex=\"-1\"><p>Places that are under ocean water at all times.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2885\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2885\"><div tabindex=\"-1\"><p>Relatively flat ocean floor, which accumulates very fine grained detrital and chemical sediments.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2683\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2683\"><div tabindex=\"-1\"><p>Rocks that are formed by sedimentary processes, including sediments lithifying and precipitation from solution.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2851\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2851\"><div tabindex=\"-1\"><p>A chemical or biochemical rock made of mainly calcite.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2849\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2849\"><div tabindex=\"-1\"><p>A very fine grained version of silica deposited with or without microfossils.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2222\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2222\"><div tabindex=\"-1\"><p>Organisms that possess vertebrate or some form of a spinal column, including humans.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1923\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1923\"><div tabindex=\"-1\"><p>Minerals that are bonded with the phosphate anion,&nbsp;PO4+3.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2176\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2176\"><div tabindex=\"-1\"><p>Any evidence of ancient life.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2586\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2586\"><div tabindex=\"-1\"><p>Middle chemical layer of the Earth, made of mainly iron and magnesium silicates. It is generally denser than the crust (except for older oceanic crust) and less dense than the core.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2580\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2580\"><div tabindex=\"-1\"><p>The outermost chemical layer of the Earth, defined by its low density and higher concentrations of lighter elements. The crust has two types: <strong>continental<\/strong>, which is the thick, more ductile, and lowest density, and <strong>oceanic<\/strong>, which is higher density, more brittle, and thinner.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2588\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2588\"><div tabindex=\"-1\"><p>An intrusive ultramafic rock, which is the main component of the mantle. The minerals in peridotite are typically olivine with some pyroxene.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1961\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1961\"><div tabindex=\"-1\"><p>General name of a mafic rock that is extrusive. Generally has a black groundmass color.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2708\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2708\"><div tabindex=\"-1\"><p>Two or more elements that can easily substitute for each other, due to similarities in ionic size and charge.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1956\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1956\"><div tabindex=\"-1\"><p>Can refer to a volcanic rock with lower silica composition, or the minerals that make up those rocks, namely olivine, pyroxene, amphibole, and biotite. Mafic rocks are darker in color and contain more minerals that are dark in color, but can contain some plagioclase feldspar. Primary mafic rocks are basalt (extrusive) and gabbro (intrusive).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2576\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2576\"><div tabindex=\"-1\"><p>The theory that the outer layer of the Earth (the lithosphere) is broken in several plates, and these plates move relative to one another, causing the major topographic features of Earth (e.g. mountains, oceans) and most earthquakes and volcanoes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2591\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2591\"><div tabindex=\"-1\"><p>A solid part&nbsp;of the lithosphere which moves as a unit, i.e. the entire plate generally moves the same direction at the same speed.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2602\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2602\"><div tabindex=\"-1\"><p>A process where an oceanic plate descends bellow a less dense plate, causing the removal of the plate from the surface. Subduction causes the largest earthquakes possible, as the subducting plate can lock as it goes down. Volcanism is also caused as the plate releases volatiles into the mantle, causing melting.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2175\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2175\"><div tabindex=\"-1\"><p>ZrSiO4.&nbsp;Relatively chemically inert with a hardness of 8.5. Common accessory mineral in igneous and metamorphic rocks, as well as detrital sediments. Uranium can substitute for zirconium, making zircon a valuable mineral in radiometric dating.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2938\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2938\"><div tabindex=\"-1\"><p>A qualitative measure of the amount of metamorphism that has occurred or the amount of a resource present in an ore.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2712\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2712\"><div tabindex=\"-1\"><p>XY(Al,Si)2O6, in which X typically equals Na, Ca, Mg, or Fe and Y typically equals Mg, Fe, or Al. Typically black to dark green, blocky, with two cleavages at ~90\u00b0. Common in mafic igneous rocks and some metamorphic rocks. Structure is a single chain of silica tetrahedra.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1964\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1964\"><div tabindex=\"-1\"><p>General name of a mafic rock that is intrusive. Has more mafic minerals than felsic minerals.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2929\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2929\"><div tabindex=\"-1\"><p>Rock more metamorphosed than phyllite, to the point that mica grains are visible. Larger porphyroblasts are sometimes present.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2713\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2713\"><div tabindex=\"-1\"><p>(RSi4O11)2, where R is a large number of different cations that can sub in. Can be many colors, but the common form, hornblende, is dark brown to black. Has two cleavages at 54\u00b0 and 126\u00b0. Crystals are typically elongated needles or diamond shapes. Common in many igneous rocks and some metamorphic rocks. Structure is a double chain of silica tetrahedra.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1928\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1928\"><div tabindex=\"-1\"><p>The typical form or forms a crystal takes when it grows.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2684\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2684\"><div tabindex=\"-1\"><p>Rocks formed via heat and pressure which change the minerals within the rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1963\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1963\"><div tabindex=\"-1\"><p>General name of an intermediate rock that is intrusive. Has about the same amount of felsic minerals and mafic minerals.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1962\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1962\"><div tabindex=\"-1\"><p>General name of a felsic rock that is intrusive. Has more felsic minerals than mafic minerals.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1914\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1914\"><div tabindex=\"-1\"><p>X1A2-3Z4O10(OH,\u202fF)2, where commonly X=K, Na, Ca; A=Al, Mg, Fe; Z=Si, Al. Has two more-common occurrences, light-colored (translucent and pearly tan) muscovite, and dark colored biotite. Has one strong cleavage, and is typically seen as sheets, in stacks or \"books.\" Common in many igneous and metamorphic rocks. Structure is two-dimensional sheets of silica tetrahedra in a hexagonal netowork.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1954\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1954\"><div tabindex=\"-1\"><p>Can refer to a volcanic rock with higher silica composition, or the minerals that make up those rocks, namely quartz, feldspar (both potassium feldspar and plagioclase feldspar), and muscovite mica. Felsic rocks are lighter in color and contain more minerals that are light in color, but can contain some biotite and amphibole. Primary felsic rocks are rhyolite (extrusive) and granite (intrusive).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1916\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1916\"><div tabindex=\"-1\"><p>Consisting of three end members:&nbsp;potassium feldspar (K-spar, KAlSi3O8), plagioclase with calcium (CaAl2Si2O8, called anorthite), and plagioclase with sodium (NaAlSi3O8, called albite). Commonly blocky, with two cleavages as ~90\u00b0. Plagioclase is typically more dull white and grey, and K-spar is more vibrant white, orange, or red. The most common mineral found within the crust, and a major component of almost all igneous rocks, some sedimentary rocks, and some metamorphic rocks. Structure is a three-dimensional framework of silica tetrahedra, with locations open for cations (K, Na, Ca).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3213\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3213\"><div tabindex=\"-1\"><p>Rock spire that is offshore and a remnant of a rock layer.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2676\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2676\"><div tabindex=\"-1\"><p>Breaking down rocks into small pieces by chemical or mechanical means.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1915\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1915\"><div tabindex=\"-1\"><p>SiO2. Transparent, but can be any color imaginable with impurities. No cleavage, hard, and commonly forms equant masses. Perfect crystals are hexagonal prisms topped with pyramidal shapes. One of the most common minerals, and is found in many different geologic settings, including the dominant component of sand on the surface of Earth. Structure is a three-dimensional network of silica tetrahedra, connected as much as possible to each other.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2581\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2581\"><div tabindex=\"-1\"><p>The thin, outer layer of the Earth which makes up the rocky bottom of the ocean basins. It is made of rocks similar to basalt, and as it cools, even become more dense than the upper mantle below.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1958\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1958\"><div tabindex=\"-1\"><p>General name of a felsic rock that is extrusive. Generally has a white, tan, or pink groundmass color.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3363\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3363\"><div tabindex=\"-1\"><p>Sedimentary rocks made of mineral grains weathered as mechanical detritus of previous rocks, e.g. sand, gravel, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3345\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3345\"><div tabindex=\"-1\"><p>Minerals with a luster similar to metal and contain metals, including valuable elements like lead, zinc, copper, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1924\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1924\"><div tabindex=\"-1\"><p>Minerals made from just a single element, bonded to itself. Examples include gold, silver, copper, and diamond, which is a native version of carbon.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3357\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3357\"><div tabindex=\"-1\"><p>A highly weathered soil deposit that consists of aluminum ores.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3325\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3325\"><div tabindex=\"-1\"><p>Valuable material in the Earth, typically used for metallic mineral resources.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1920\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1920\"><div tabindex=\"-1\"><p>Minerals based on bonds to column 17 halogens, such as chlorine and fluorine.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2843\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2843\"><div tabindex=\"-1\"><p>An evaporite mineral, CaSo4\u20222H2O. Has one cleavage, hardness of 2. Typically clear or white.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2682\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2682\"><div tabindex=\"-1\"><p>The process of turning sediment into a sedimentary rocks, including deposition, compaction, and cementation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3091\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3091\"><div tabindex=\"-1\"><p>Waves that change direction due to changing speeds, typically caused by a change in density of the medium.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2813\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2813\"><div tabindex=\"-1\"><p>An acid that forms from carbon dioxide and water. It is a large contributor to chemical weathering.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2842\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2842\"><div tabindex=\"-1\"><p>A chemical sedimentary rock that forms as water evaporates.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2834\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2834\"><div tabindex=\"-1\"><p>A rock primarily made of sand.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1933\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1933\"><div tabindex=\"-1\"><p>A feature with no internal structure, habit, or layering.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2940\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2940\"><div tabindex=\"-1\"><p>A specific chemical composition that forms different minerals and different temperatures and pressures. Quartz has several different polymorphs, including coesite, tridimite, and stishovite.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3324\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3324\"><div tabindex=\"-1\"><p>Place where material is extracted from the Earth for human use.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1925\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1925\"><div tabindex=\"-1\"><p>The shine a mineral takes on, based on the way light reflects off of a mineral. This is typically divided into two main categories: metallic (metal-like shine) and nonmetallic (non metal-like shine).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1926\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1926\"><div tabindex=\"-1\"><p>The color(s) that a mineral produces when powdered or rubbed against a hard surface, usually a porcelain tile.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1927\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1927\"><div tabindex=\"-1\"><p>The ease or difficulty in scratching a mineral, measured by the qualitative Mohs hardness scale, which ranges from soft talc (#1 on the scale) to hard diamond (#10 on the scale).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1934\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1934\"><div tabindex=\"-1\"><p>A break within a rock that has no relative movement between the sides. Caused by cooling, pressure release, tectonic forces, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3346\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3346\"><div tabindex=\"-1\"><p>Minerals that have a luster that is not similar to metal, and typically do not contain valuable metals like copper, lead, zinc, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1929\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1929\"><div tabindex=\"-1\"><p>A mineral that shows no crystal habit, either because it is not prone to have a habit, or because it grew in a way that it was confined so it could not grow with its normal habit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1930\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1930\"><div tabindex=\"-1\"><p>A mineral which only shows some characteristics of its true crystal habit, and is not perfectly grown.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1931\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1931\"><div tabindex=\"-1\"><p>A mineral that perfectly shows its true crystal habit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2860\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2860\"><div tabindex=\"-1\"><p>Thin (less than 1 cm) beds of rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1932\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1932\"><div tabindex=\"-1\"><p>Stubby, not long in any direction.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1935\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1935\"><div tabindex=\"-1\"><p>Fractures that have a circular appearance.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1181\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1181\"><div tabindex=\"-1\"><p>Place where lava is erupted at the surface.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_1937\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_1937\"><div tabindex=\"-1\"><p>Related to density; the ratio of the weight of a mineral vs. the weight of an equal volume of water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2647\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2647\"><div tabindex=\"-1\"><p>An observation which is based on non-numerical data. While these types of observations are not preferred, they can still be useful.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2645\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2645\"><div tabindex=\"-1\"><p>An observation which is influenced by the observer's personal bias.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2925\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2925\"><div tabindex=\"-1\"><p>Linear alignment of minerals within a rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_3096\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_3096\"><div tabindex=\"-1\"><p>A process of using 3D seismic arrays to get subsurface images.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2848\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2848\"><div tabindex=\"-1\"><p>A sedimentary rock that formed long ago as free oxygen changed the solubility of iron, causing layers of iron rich and iron-poor sediments to form in thin layers, or bands.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_233_2960\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_233_2960\"><div tabindex=\"-1\"><p>An extensive, distinct, and mapped set of geologic layers.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":83,"menu_order":3,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-233","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":19,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapters\/233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/wp\/v2\/users\/83"}],"version-history":[{"count":3,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapters\/233\/revisions"}],"predecessor-version":[{"id":3404,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapters\/233\/revisions\/3404"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/parts\/19"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapters\/233\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/wp\/v2\/media?parent=233"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/pressbooks\/v2\/chapter-type?post=233"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/wp\/v2\/contributor?post=233"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/accintrogeology\/wp-json\/wp\/v2\/license?post=233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}