Editing Mineral (section)

===Non-silicates===

====Native elements====
{{main article|Native element minerals}}
[[File:Gold-mz4b.jpg|left|thumb|Native gold. Rare specimen of stout crystals growing off of a central stalk, size 3.7 x 1.1 x 0.4 cm, from Venezuela.]]
[[native element minerals|Native elements]] are those that are not chemically bonded to other elements. This mineral group includes [[native metal]]s, semi-metals, and non-metals, and various alloys and solid solutions. The metals are held together by metallic bonding, which confers distinctive physical properties such as their shiny metallic lustre, ductility and malleability, and electrical conductivity. Native elements are subdivided into groups by their structure or chemical attributes.

The gold group, with a cubic close-packed structure, includes metals such as gold, silver, and copper. The platinum group is similar in structure to the gold group. The iron-nickel group is characterized by several iron-nickel alloy species. Two examples are [[kamacite]] and [[taenite]], which are found in iron meteorites; these species differ by the amount of Ni in the alloy; kamacite has less than 5–7% nickel and is a variety of [[telluric iron|native iron]], whereas the nickel content of taenite ranges from 7–37%. Arsenic group minerals consist of semi-metals, which have only some metallic traits; for example, they lack the malleability of metals. Native carbon occurs in two allotropes, graphite and diamond; the latter forms at very high pressure in the mantle, which gives it a much stronger structure than graphite.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 644–48</ref>

====Sulfides====
{{main article|Sulfide minerals}}
[[File:Cinnabar on Dolomite.jpg|right|thumb|Red cinnabar (HgS), a mercury ore, on dolomite.]]
[[File:Geodized brachiopod.jpg|right|thumb|Sphalerite crystal partially encased in [[calcite]] from the [[Devonian]] [[Milwaukee Formation]] of [[Wisconsin]]]]
The [[sulfide minerals]] are chemical compounds of one or more metals or semimetals with a [[chalcogen]] or [[pnictogen]], of which sulfur is most common. Tellurium, arsenic, or selenium can substitute for the sulfur. Sulfides tend to be soft, brittle minerals with a high specific gravity. Many powdered sulfides, such as pyrite, have a sulfurous smell when powdered. Sulfides are susceptible to weathering, and many readily dissolve in water; these dissolved minerals can be later redeposited, which creates enriched secondary ore deposits.<ref>{{harvnb|Chesterman|Lowe|2008}}, p. 357</ref> Sulfides are classified by the ratio of the metal or semimetal to the sulfur, such as M:S equal to 2:1, or 1:1.<ref>{{harvnb|Dyar|Gunter|2008}}, p. 649</ref> Many [[sulfide mineral]]s are economically important as metal [[ore]]s; examples include [[sphalerite]] (ZnS), an ore of zinc, [[galena]] (PbS), an ore of lead, [[cinnabar]] (HgS), an ore of mercury, and [[molybdenite]] (MoS<sub>2</sub>, an ore of molybdenum.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 651–54</ref> Pyrite (FeS<sub>2</sub>), is the most commonly occurring sulfide, and can be found in most geological environments. It is not, however, an ore of iron, but can be instead oxidized to produce [[sulfuric acid]].<ref>{{harvnb|Dyar|Gunter|2008}}, p. 654</ref> Related to the sulfides are the rare [[Sulfosalt mineral|sulfosalts]], in which a metallic element is bonded to sulfur and a semimetal such as [[antimony]], [[arsenic]], or [[bismuth]]. Like the sulfides, sulfosalts are typically soft, heavy, and brittle minerals.<ref>{{harvnb|Chesterman|Lowe|2008}}, p. 383</ref>

====Oxides====
{{main article|Oxide minerals}}
[[Oxide minerals]] are divided into three categories: simple oxides, hydroxides, and multiple oxides. Simple oxides are characterized by O<sup>2−</sup> as the main anion and primarily ionic bonding. They can be further subdivided by the ratio of oxygen to the cations. The [[periclase]] group consists of minerals with a 1:1 ratio. Oxides with a 2:1 ratio include [[cuprite]] (Cu<sub>2</sub>O) and water ice. Corundum group minerals have a 2:3 ratio, and includes minerals such as [[corundum]] (Al<sub>2</sub>O<sub>3</sub>), and [[hematite]] (Fe<sub>2</sub>O<sub>3</sub>). Rutile group minerals have a ratio of 1:2; the eponymous species, rutile (TiO<sub>2</sub>) is the chief ore of [[titanium]]; other examples include [[cassiterite]] (SnO<sub>2</sub>; ore of [[tin]]), and [[pyrolusite]] (MnO<sub>2</sub>; ore of [[manganese]]).<ref>{{harvnb|Chesterman|Lowe|2008}}, pp. 400–03</ref><ref>{{harvnb|Dyar|Gunter|2008}}, pp. 657–60</ref>  In hydroxides, the dominant anion is the hydroxyl ion, OH<sup>−</sup>. [[Bauxite]]s are the chief aluminium ore, and are a heterogeneous mixture of the hydroxide minerals [[diaspore]], [[gibbsite]], and [[bohmite]]; they form in areas with a very high rate of chemical weathering (mainly tropical conditions).<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 663–64</ref>  Finally, multiple oxides are compounds of two metals with oxygen. A major group within this class are the [[spinel group|spinels]], with a general formula of X<sup>2+</sup>Y<sup>3+</sup><sub>2</sub>O<sub>4</sub>. Examples of species include [[spinel]] (MgAl<sub>2</sub>O<sub>4</sub>), [[chromite]] (FeCr<sub>2</sub>O<sub>4</sub>), and [[magnetite]] (Fe<sub>3</sub>O<sub>4</sub>). The latter is readily distinguishable by its strong magnetism, which occurs as it has iron in two [[oxidation state]]s (Fe<sup>2+</sup>Fe<sup>3+</sup><sub>2</sub>O<sub>4</sub>), which makes it a multiple oxide instead of a single oxide.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 660–63</ref>

====Halides====
{{main article|Halide minerals}}
[[File:Halite-Nahcolite-51411.jpg|left|thumb|Pink cubic [[halite]] (NaCl; halide class) crystals on a [[nahcolite]] matrix (NaHCO<sub>3</sub>; a carbonate, and mineral form of sodium bicarbonate, used as [[baking soda]]).]]

The [[halide minerals]] are compounds in which a [[halogen]] (fluorine, chlorine, iodine, or bromine) is the main anion. These minerals tend to be soft, weak, brittle, and water-soluble. Common examples of halides include halite (NaCl, table salt), [[sylvite]] (KCl), and [[fluorite]] (CaF<sub>2</sub>). Halite and sylvite commonly form as [[evaporite]]s, and can be dominant minerals in chemical sedimentary rocks. [[Cryolite]], Na<sub>3</sub>AlF<sub>6</sub>, is a key mineral in the extraction of aluminium from [[bauxite]]s; however, as the only significant occurrence at [[Ivittuut]], [[Greenland]], in a granitic pegmatite, was depleted, synthetic cryolite can be made from fluorite.<ref>{{harvnb|Chesterman|Lowe|2008}}, pp. 425–30</ref>

====Carbonates====
{{main article|Carbonate minerals}}
The [[carbonate minerals]] are those in which the main anionic group is carbonate, [CO<sub>3</sub>]<sup>2−</sup>. Carbonates tend to be brittle, many have rhombohedral cleavage, and all react with acid.<ref>{{harvnb|Chesterman|Lowe|2008}}, p. 431</ref> Due to the last characteristic, field geologists often carry dilute hydrochloric acid to distinguish carbonates from non-carbonates. The reaction of acid with carbonates, most commonly found as the polymorph calcite and [[aragonite]] (CaCO<sub>3</sub>), relates to the dissolution and precipitation of the mineral, which is a key in the formation of limestone caves, features within them such as stalactite and stalagmites, and [[karst]] landforms. Carbonates are most often formed as biogenic or chemical sediments in marine environments. The carbonate group is structurally a triangle, where a central C<sup>4+</sup> cation is surrounded by three O<sup>2−</sup> anions; different groups of minerals form from different arrangements of these triangles.<ref>{{harvnb|Dyar|Gunter|2008}}, p. 667</ref> The most common carbonate mineral is calcite, which is the primary constituent of sedimentary limestone and metamorphic marble. Calcite, CaCO<sub>3</sub>, can have a significant percentage of magnesium substituting for calcium. Under high-Mg conditions, its polymorph aragonite will form instead; the marine geochemistry in this regard can be described as an [[aragonite sea|aragonite]] or [[calcite sea]], depending on which mineral preferentially forms. [[Dolomite (mineral)|Dolomite]] is a double carbonate, with the formula CaMg(CO<sub>3</sub>)<sub>2</sub>. Secondary dolomitization of limestone is common, in which calcite or aragonite are converted to dolomite; this reaction increases pore space (the unit cell volume of dolomite is 88% that of calcite), which can create a reservoir for oil and gas. These two mineral species are members of eponymous mineral groups: the calcite group includes carbonates with the general formula XCO<sub>3</sub>, and the dolomite group constitutes minerals with the general formula XY(CO<sub>3</sub>)<sub>2</sub>.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 668–69</ref>

====Sulfates====
{{main article|Sulfate minerals}}
[[File:Roses des Sables Tunisie.jpg|right|thumb|upright=1.15|Gypsum desert rose]]
The [[sulfate mineral]]s all contain the sulfate anion, [SO<sub>4</sub>]<sup>2−</sup>. They tend to be transparent to translucent, soft, and many are fragile.<ref>{{harvnb|Chesterman|Lowe|2008}}, p. 453</ref> Sulfate minerals commonly form as [[evaporite]]s, where they precipitate out of evaporating saline waters. Sulfates can also be found in hydrothermal vein systems associated with sulfides,<ref>{{harvnb|Chesterman|Lowe|2008}}, pp. 456–57</ref> or as oxidation products of sulfides.<ref>{{harvnb|Dyar|Gunter|2008}}, p. 674</ref> Sulfates can be subdivided into anhydrous and hydrous minerals. The most common hydrous sulfate by far is [[gypsum]], CaSO<sub>4</sub>⋅2H<sub>2</sub>O. It forms as an evaporite, and is associated with other evaporites such as calcite and halite; if it incorporates sand grains as it crystallizes, gypsum can form [[Desert rose (crystal)|desert roses]]. Gypsum has very low thermal conductivity and maintains a low temperature when heated as it loses that heat by dehydrating; as such, gypsum is used as an insulator in materials such as plaster and drywall. The anhydrous equivalent of gypsum is [[anhydrite]]; it can form directly from seawater in highly arid conditions. The barite group has the general formula XSO<sub>4</sub>, where the X is a large 12-coordinated cation. Examples include [[barite]] (BaSO<sub>4</sub>), [[Celestine (mineral)|celestine]] (SrSO<sub>4</sub>), and [[anglesite]] (PbSO<sub>4</sub>); anhydrite is not part of the barite group, as the smaller Ca<sup>2+</sup> is only in eight-fold coordination.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 672–73</ref>

====Phosphates====
{{main article|Phosphate minerals}}
The [[phosphate minerals]] are characterized by the tetrahedral [PO<sub>4</sub>]<sup>3−</sup> unit, although the structure can be generalized, and phosphorus is replaced by antimony, arsenic, or vanadium. The most common phosphate is the [[apatite]] group; common species within this group are fluorapatite (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>F), chlorapatite (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>Cl) and hydroxylapatite (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)). Minerals in this group are the main crystalline constituents of teeth and bones in vertebrates. The relatively abundant [[monazite]] group has a general structure of ATO<sub>4</sub>, where T is phosphorus or arsenic, and A is often a [[rare-earth element]] (REE). Monazite is important in two ways: first, as a REE "sink", it can sufficiently concentrate these elements to become an ore; secondly, monazite group elements can incorporate relatively large amounts of uranium and thorium, which can be used in [[monazite geochronology]] to date the rock based on the decay of the U and Th to lead.<ref>{{harvnb|Dyar|Gunter|2008}}, pp. 675–80</ref>

====Organic minerals====
{{main article|Organic mineral}}
The Strunz classification includes a class for [[Strunz classification#Class: organic compounds|organic minerals]]. These rare compounds contain [[Organic compound|organic carbon]], but can be formed by a geologic process. For example, [[whewellite]], CaC<sub>2</sub>O<sub>4</sub>⋅H<sub>2</sub>O is an [[oxalate]] that can be deposited in hydrothermal ore veins. While hydrated calcium oxalate can be found in coal seams and other sedimentary deposits involving organic matter, the hydrothermal occurrence is not considered to be related to biological activity.<ref name="{{harvnb|Dyar|Gunter|2008}}, p. 681"/>