Mineral 19053 225981954 2008-07-16T09:10:43Z Wavelength 271168 /* See also */ adding 1 internal link: * [[Strunz classification]] ([[WP:O]]) {{otheruses}} A '''mineral''' is a naturally occurring substance formed through [[Geology|geological]] processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. A [[Rock (geology)|rock]], by comparison, is an aggregate of minerals and need not have a specific chemical composition. Minerals range in composition from pure [[chemical element|elements]] and simple [[Salt (chemistry)|salt]]s to very complex [[silicate]]s with thousands of known forms.<ref name=Klein>Klein, Cornelis and Cornelius Hurlbut, Jr. (1985) ''Manual of Mineralogy'', Wiley, 20th ed., ISBN 0-471-80580-7</ref> The study of minerals is called [[mineralogy]]. [[Image:Different minerals.jpg|right|300px|thumb|An assortment of minerals.]] ==Mineral definition and classification== To be classified as a true mineral, a substance must be a [[solid]] and have a [[crystalline]] structure. It must also be a naturally occurring, homogeneous substance with a defined chemical composition. Traditional definitions excluded ''organically derived'' material. However, the [[International Mineralogical Association]] in 1995 adopted a new definition: :a mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes.<ref name=Nickel> http://www.minsocam.org/msa/ima/ima98(04).pdf Ernest H. Nickel, 1995, ''The definition of a mineral'', The Canadian Mineralogist, vol. 33, pp. 689 - 690</ref> The modern classifications include an ''organic class'' - in both the new Dana and the Strunz classification schemes.<ref name=Dana> http://www.mindat.org/dana.php?a=50 Dana Classification 8th edition - ORGANIC COMPOUNDS</ref><ref name=Strunz> http://www.mindat.org/strunz.php?a=9 Strunz Classification - Organic Compounds</ref> The [[chemical]] composition may vary between [[Endmember (mineralogy)|end member]]s of a mineral system. For example the [[plagioclase]] [[feldspar]]s comprise a continuous series from [[sodium]]-rich [[albite]] (NaAlSi<sub>3</sub>O<sub>8</sub>) to [[calcium]]-rich [[anorthite]] (CaAl<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>) with four recognized intermediate compositions between. Mineral-like substances that don't strictly meet the definition are sometimes classified as [[mineraloid]]s. Other natural-occurring substances are [[nonmineral]]s. [[Industrial minerals]] is a market term and refers to commercially valuable mined materials (see also Minerals and Rocks section below). A '''[[crystal structure]]''' is the orderly geometric spatial arrangement of [[atom]]s in the internal structure of a mineral. There are 14 basic [[crystal lattice]] arrangements of atoms in three dimensions, and these are referred to as the 14 "[[Bravais lattice]]s". Each of these lattices can be classified into one of the six [[crystal]] systems, and all crystal structures currently recognized fit in one Bravais lattice and one crystal system. This crystal structure is based on regular internal atomic or [[ion]]ic arrangement that is often expressed in the geometric form that the crystal takes. Even when the mineral grains are too small to see or are irregularly shaped, the underlying crystal structure is always periodic and can be determined by [[X-ray]] diffraction. Chemistry and crystal structure together define a mineral. In fact, two or more minerals may have the same chemical composition, but differ in crystal structure (these are known as ''polymorphs''). For example, [[pyrite]] and [[marcasite]] are both iron sulfide, but their arrangement of atoms differs. Similarly, some minerals have different chemical compositions, but the same crystal structure: for example, [[halite]] (made from sodium and [[chlorine]]), [[galena]] (made from [[lead]] and [[sulfur]]) and [[periclase]] (made from [[magnesium]] and [[oxygen]]) all share the same cubic crystal structure. Crystal structure greatly influences a mineral's physical properties. For example, though [[diamond]] and [[graphite]] have the same composition (both are pure [[carbon]]), graphite is very soft, while diamond is the hardest of all known minerals. This happens because the carbon atoms in graphite are arranged into sheets which can slide easily past each other, while the carbon atoms in diamond form a strong, interlocking three-dimensional network. There are currently more than 4,000 known minerals, according to the [[International Mineralogical Association]], which is responsible for the approval of and naming of new mineral species found in nature. Of these, perhaps 100 can be called "common," 50 are "occasional," and the rest are "rare" to "extremely rare." === Differences between minerals and rocks === A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a specific crystalline structure. A [[Rock (geology)|rock]] is an aggregate of one or more minerals. (A rock may also include organic remains and [[mineraloid]]s.) Some rocks are predominantly composed of just one mineral. For example, [[limestone]] is a [[sedimentary rock]] composed almost entirely of the mineral [[calcite]]. Other rocks contain many minerals, and the specific minerals in a rock can vary widely. Some minerals, like [[quartz]], [[mica]] or [[feldspar]] are common, while others have been found in only one or two locations worldwide. The vast majority of the rocks of the [[Earth's crust]] consist of quartz, feldspar, mica, [[Chlorite group|chlorite]], [[kaolin]], calcite, [[epidote]], [[olivine]], [[augite]], [[hornblende]], [[magnetite]], [[hematite]], [[limonite]] and a few other minerals.<ref name=EB1911>{{1911|article=Petrology}}</ref> Over half of the mineral species known are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains. Commercially valuable minerals and rocks are referred to as [[industrial minerals]]. Rocks from which minerals are [[Mining|mined]] for economic purposes are referred to as [[ores]] (the rocks and minerals that remain, after the desired mineral has been separated from the ore, are referred to as [[tailings]]). ==== Mineral composition of rocks ==== A main determining factor in the formation of minerals in a rock mass is the chemical composition of the mass, for a certain mineral can be formed only when the necessary elements are present in the rock. Calcite is most common in [[limestone]]s, as these consist essentially of [[calcium carbonate]]; quartz is common in sandstones and in certain [[igneous rocks]] which contain a high percentage of [[silica]]. Other factors are of equal importance in determining the natural association or [[paragenesis]] of rock-forming minerals, principally the mode of origin of the rock and the stages through which it has passed in attaining its present condition. Two rock masses may have very much the same bulk composition and yet consist of entirely different assemblages of minerals. The tendency is always for those compounds to be formed which are stable under the conditions under which the rock mass originated. A [[granite]] arises by the consolidation of a molten [[magma]] at high temperatures and great pressures and its component minerals are those stable under such conditions. Exposed to moisture, [[carbonic acid]] and other subaerial agents at the ordinary temperatures of the Earth's surface, some of these original minerals, such as quartz and white mica are relatively stable and remain unaffected; others [[Weathering|weather]] or decay and are replaced by new combinations. The [[feldspar]] passes into [[kaolinite]], [[muscovite]] and quartz, and any [[mafic]] minerals such as [[pyroxene]]s, [[amphibole]]s or [[biotite]] have been present they are often altered to [[Chlorite group|chlorite]], [[epidote]], [[rutile]] and other substances. These changes are accompanied by disintegration, and the rock falls into a loose, incoherent, earthy mass which may be regarded as a sand or soil. The materials thus formed may be washed away and deposited as sandstone or siltstone. The structure of the original rock is now replaced by a new one; the mineralogical constitution is profoundly altered; but the bulk chemical composition may not be very different. The sedimentary rock may again undergo [[metamorphism]]. If penetrated by igneous rocks it may be recrystallized or, if subjected to enormous pressures with heat and movement during [[Orogeny|mountain building]], it may be converted into a [[gneiss]] not very different in mineralogical composition though radically different in structure to the granite which was its original state.<ref name=EB1911 /> === Physical properties of minerals === Classifying minerals can range from simple to very difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex chemical or [[X-ray diffraction]] analysis; these methods, however, can be costly and time-consuming. Physical properties commonly used are:<ref name=Klein/> * ''Crystal structure and habit'': See the above discussion of crystal structure. A mineral may show good crystal habit or form, or it may be massive, granular or compact with only microscopically visible crystals. [[Image:Talc block.jpg|thumb|100px|Talc]] [[Image:Rough diamond.jpg|thumb|100px|Rough diamond.]] * ''[[Hardness (materials science)|Hardness]]'': the physical hardness of a mineral is usually measured according to the [[Mohs scale of mineral hardness|Mohs scale]]. This scale is relative and goes from 1 to 10. Minerals with a given Mohs hardness can scratch the surface of any mineral that has a lower hardness than itself. **Mohs hardness scale:<ref>http://volcanoes.usgs.gov/Products/Pglossary/mineral.html USGS Photo glossary of volcano terms</ref> # [[Talc]] Mg<sub>3</sub>Si<sub>4</sub>O<sub>10</sub>(OH)<sub>2</sub> # [[Gypsum]] CaSO<sub>4</sub>·2H<sub>2</sub>O # [[Calcite]] CaCO<sub>3</sub> # [[Fluorite]] CaF<sub>2</sub> # [[Apatite]] Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH,Cl,F) # [[Orthoclase]] KAlSi<sub>3</sub>O<sub>8</sub> # [[Quartz]] SiO<sub>2</sub> # [[Topaz]] Al<sub>2</sub>SiO<sub>4</sub>(OH,F)<sub>2</sub> # [[Corundum]] Al<sub>2</sub>O<sub>3</sub> # [[Diamond]] C (pure carbon) * ''[[Lustre (mineralogy)|Lustre]]'' indicates the way a mineral's surface interacts with light and can range from dull to glassy (vitreous). **Metallic -high reflectivity like metal: [[galena]] and [[pyrite]] **Sub-metallic -slightly less than metallic reflectivity: [[magnetite]] **Non-metallic lusters: ***''Adamantine'' - brilliant, the luster of [[diamond]] also [[cerussite]] and [[anglesite]] ***''Vitreous'' -the luster of a broken glass: quartz ***''Pearly'' - iridescent and pearl-like: talc and [[apophyllite]] ***''Resinous'' - the luster of resin: [[sphalerite]] and [[sulfur]] ***''Silky'' - a soft light shown by fibrous materials: gypsum and [[chrysotile]] ***Dull/earthy -shown by finely crystallized minerals: the kidney ore variety of [[hematite]] * ''[[Color]]'' indicates the appearance of the mineral in reflected light or transmitted light for translucent minerals (i.e. what it looks like to the naked eye). **''Iridescence'' - the ''play of colors'' due to surface or internal interference. [[Labradorite]] exhibits internal iridescence whereas hematite and sphalerite often show the surface effect. * ''[[Streak (mineralogy)|Streak]]'' refers to the color of the powder a mineral leaves after rubbing it on an unglazed porcelain ''streak plate''. Note that this is not always the same color as the original mineral. * ''[[Cleavage (crystal)|Cleavage]]'' describes the way a mineral may split apart along various planes. In thin sections, cleavage is visible as thin parallel lines across a mineral. * ''Fracture'' describes how a mineral breaks when broken contrary to its natural cleavage planes. ** ''Chonchoidal fracture'' is a smooth curved fracture with concentric ridges of the type shown by glass. ** ''Hackley'' is jagged fracture with sharp edges. ** ''Fibrous'' ** ''Irregular'' * ''[[Specific gravity]]'' relates the mineral [[mass]] to the mass of an equal volume of water, namely the [[density]] of the material. While most minerals, including all the common rock-forming minerals, have a specific gravity of 2.5 - 3.5, a few are noticeably more or less dense, e.g. several sulfide minerals have high specific gravity compared to the common rock-forming minerals. * Other properties: [[fluorescence]] (response to ultraviolet light), [[magnetism]], [[radioactivity]], [[Tenacity (geology)|tenacity]] (response to mechanical induced changes of shape or form), [[piezoelectricity]] and reactivity to dilute [[acid]]s. === Chemical properties of minerals === Minerals may be classified according to chemical composition. They are here categorized by [[anion]] group. The list below is in approximate order of their abundance in the Earth's [[Crust (geology)|crust]]. The list follows the [[James Dwight Dana|Dana]] classification system.<ref name=Klein /><ref>http://www.minerals.net/mineral/sort-met.hod/dana/dana.htm Dana classification - Minerals.net</ref> ==== Silicate class ==== [[Image:Quartz Crystal.jpg|thumb|[[quartz]]]] The largest group of minerals by far are the '''[[Silicate minerals|silicates]]''' (most rocks are ≥95% silicates), which are composed largely of [[silicon]] and [[oxygen]], with the addition of ions such as [[aluminium]], [[magnesium]], [[iron]], and [[calcium]]. Some important rock-forming silicates include the [[feldspar]]s, [[quartz]], [[olivine]]s, [[pyroxene]]s, [[amphibole]]s, [[garnet]]s, and [[mica]]s. ==== Carbonate class ==== The '''[[carbonate minerals]]''' consist of those minerals containing the anion (CO<sub>3</sub>)<sup>2-</sup> and include [[calcite]] and [[aragonite]] (both calcium carbonate), [[dolomite]] (magnesium/calcium carbonate) and [[siderite]] (iron carbonate). Carbonates are commonly deposited in marine settings when the shells of dead [[plankton]]ic life settle and accumulate on the sea floor. Carbonates are also found in [[evaporite|evaporitic]] settings (e.g. the [[Great Salt Lake]], [[Utah]]) and also in [[karst]] regions, where the dissolution and reprecipitation of carbonates leads to the formation of [[cave]]s, [[stalactite]]s and [[stalagmite]]s. The carbonate class also includes the [[nitrate]] and [[borate]] minerals. ==== Sulfate class ====<!-- This section is linked from [[Sulfur]] --> '''[[Sulfate]]s''' all contain the sulfate anion, SO<sub>4</sub><sup>2-</sup>. Sulfates commonly form in [[evaporite|evaporitic]] settings where highly saline waters slowly evaporate, allowing the formation of both sulfates and halides at the water-sediment interface. Sulfates also occur in [[hydrothermal]] vein systems as gangue minerals along with [[sulfide]] [[ore]] minerals. Another occurrence is as secondary [[oxidation]] products of original sulfide minerals. Common sulfates include [[anhydrite]] (calcium sulfate), [[Celestine (mineral)|celestine]] (strontium sulfate), [[barite]] (barium sulfate), and [[gypsum]] (hydrated calcium sulfate). The sulfate class also includes the [[chromate]], [[molybdate]], [[selenate]], [[sulfite]], [[tellurate]], and [[tungstate]] minerals. ==== Halide class ==== [[Image:Halite(Salt)USGOV.jpg|thumb|[[Halite]]]] The '''[[halide]]s''' are the group of minerals forming the natural [[salt]]s and include [[fluorite]] (calcium fluoride), [[halite]] (sodium chloride), [[sylvite]] (potassium chloride), and [[sal ammoniac]] (ammonium chloride). Halides, like sulfates, are commonly found in evaporitic settings such as [[Playa|playa lake]]s and landlocked seas such as the [[Dead Sea]] and Great Salt Lake. The halide class includes the [[fluoride]], [[chloride]], [[bromide]] and [[iodide]] minerals. ==== Oxide class ==== '''[[Oxide]]s''' are extremely important in [[mining]] as they form many of the [[ores]] from which valuable metals can be extracted. They also carry the best record of changes in the [[Earth's magnetic field]]. They commonly occur as precipitates close to the Earth's surface, [[oxidation]] products of other minerals in the near surface [[weathering]] zone, and as accessory minerals in igneous rocks of the crust and [[Mantle (geology)|mantle]]. Common oxides include [[hematite]] (iron oxide), [[magnetite]] (iron oxide), [[chromite]] (iron chromium oxide), [[spinel]] (magnesium aluminium oxide - a common component of the mantle), [[ilmenite]] (iron titanium oxide), [[rutile]] (titanium dioxide), and [[ice]] (hydrogen oxide). The oxide class includes the oxide and the [[hydroxide]] minerals. ==== Sulfide class ====<!-- This section is linked from [[Sulfur]] --> Many '''[[sulfide mineral]]s''' are economically important as metal [[ore]]s. Common sulfides include [[pyrite]] (iron sulfide - commonly known as ''fools' gold''), [[chalcopyrite]] (copper iron sulfide), [[pentlandite]] (nickel iron sulfide), and galena (lead sulfide). The sulfide class also includes the [[selenide]]s, the [[telluride (chemistry)|telluride]]s, the [[arsenide]]s, the [[antimonide]]s, the bismuthinides, and the [[sulfosalt]]s (sulfur and a second anion such as arsenic). ==== Phosphate class ==== The '''[[phosphate mineral]]''' group actually includes any mineral with a tetrahedral unit AO<sub>4</sub> where A can be [[phosphorus]], [[antimony]], [[arsenic]] or [[vanadium]]. By far the most common phosphate is [[apatite]] which is an important [[biology|biological]] mineral found in teeth and bones of many animals. The phosphate class includes the phosphate, [[arsenate]], [[vanadate]], and [[antimonate]] minerals. ==== Element class ==== The elemental group includes metals and intermetallic elements (gold, silver, copper), semi-metals and non-metals (antimony, bismuth, graphite, sulfur). This group also includes natural alloys, such as [[electrum]] (a natural alloy of gold and silver), phosphides, silicides, nitrides and carbides (which are usually only found naturally in a few rare meteorites). ==== Organic class ==== The organic mineral class includes biogenic substances in which geological processes have been a part of the genesis or origin of the existing compound.<ref name=Nickel /> Minerals of the organic class include various oxalates, mellitates, citrates, cyanates, acetates, formates, hydrocarbons and other miscellaneous species.<ref name=Dana /> Examples include [[whewellite]], [[moolooite]], [[mellite]], [[fichtelite]], [[carpathite]], [[evenkite]] and [[abelsonite]]. ==See also== * [[List of minerals|A list of minerals]] with associated Wikipedia articles * [[List of minerals (complete)|A comprehensive list of minerals]] * [[Tucson Gem & Mineral Show]] * [[Industrial minerals]] * [[Mineral water]], water containing minerals or other dissolved substances that alter its taste or give it therapeutic value * [[Mineral processing]] * [[Mineral wool]] * [[Mining]] * [[Norman L. Bowen]] * [[Quarry]] * [[Dietary mineral]] * [[Rocks]] * [[Strunz classification]] == External links == {{Commonscat|Minerals}} *[http://www.minerals.net/index.htm Minerals.net] *[http://www.mindat.org/index.php mindat.org Mindat database] *[http://webmineral.com Webmineral.com] *[http://www.mineralatlas.com Mineral atlas with properties, photos] == References == <references /> [[Category:Mineralogy]] [[Category:Minerals| ]] {{Link FA|bs}} [[af:Mineraal]] [[ar:معدن]] [[zh-min-nan:Khòng-bu̍t]] [[be:Мінерал]] [[bs:Minerali]] [[bg:Минерал]] [[ca:Mineral]] [[cs:Minerál]] [[cy:Mwyn]] [[da:Mineral]] [[de:Mineral]] [[et:Mineraal]] [[el:Ορυκτό]] [[es:Mineral]] [[eo:Mineralo]] [[eu:Mea]] [[fa:کانی (معدن)]] [[fr:Minéral]] [[ga:Mianra]] [[gl:Mineral]] [[ko:광물]] [[hi:खनिज]] [[hr:Minerali]] [[id:Mineral]] [[is:Steind]] [[it:Minerale]] [[he:מינרל]] [[kk:Минерал]] [[lo:ແຮ່ທາດ]] [[la:Minerale]] [[lv:Minerāls]] [[lt:Mineralas]] [[lmo:Mineràj]] [[hu:Ásvány]] [[mk:Минерал]] [[ms:Mineral]] [[mn:Эрдэс]] [[nl:Mineraal]] [[ja:鉱物]] [[no:Mineral]] [[nn:Mineral]] [[nds:Mineral]] [[pl:Minerał]] [[pt:Mineral]] [[ro:Mineral]] [[qu:Qiqlla]] [[ru:Минерал]] [[scn:Minirali]] [[simple:Mineral]] [[sk:Nerast]] [[sl:Mineral]] [[sr:Минерал]] [[sh:Minerali]] [[su:Mineral]] [[fi:Mineraali]] [[sv:Mineral]] [[ta:கனிமம்]] [[th:แร่]] [[vi:Khoáng vật]] [[tr:Mineral]] [[uk:Мінерали]] [[yi:מינעראל]] [[zh:礦物]]