Editing Chromite

{{Short description|Crystalline mineral}}
{{about|the mineral|the chromium(III) cation and its salts|Chromite (compound)}}
{{Infobox mineral
| name        = Chromite
| category    = [[Oxide minerals]] <br>[[Spinel group]] <br>Spinel structural group
| boxwidth    =
| image       = File:Chromite-201529.jpg
| imagesize   = 260px
| caption     = [[Octahedron|Octahedral]] chromite crystal from the Freetown Layered Complex in [[Sierra Leone]], [[Africa]] (size: 1.3 x 1.2 x 1.2&nbsp;cm)
| formula     = (Fe, Mg)Cr<sub>2</sub>O<sub>4</sub>
| IMAsymbol   = Chr<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>  
| strunz      = 4.BB.05
| system      = [[Cubic crystal system|Isometric]]
| class       = Hexoctahedral (m{{overline|3}}m) <br/>[[H-M symbol]]: (4/m {{overline|3}} 2/m)
| symmetry    = ''Fd{{overline|3}}m'' (no. 227)
| unit cell   = a = 8.344&nbsp;Å; Z&nbsp;=&nbsp;8
| color       = Black to brownish black; brown to brownish black on thin edges in transmitted light
| habit       = Octahedral rare; massive to granular
| twinning    = Spinel law on {Ill} 
| cleavage    = None, parting may develop along {III}
| fracture    = Uneven
| tenacity    = Brittle
| mohs        = 5.5
| luster      = Resinous, Greasy, Metallic, Sub-Metallic, Dull
| refractive  = n = 2.08–2.16
| opticalprop = Isotropic
| birefringence =
| pleochroism =
| streak      = Brown
| gravity     = 4.5–4.8
| melt        =
| fusibility  =
| diagnostic  =
| solubility  =
| diaphaneity = Translucent to opaque
| other       = Weakly magnetic
| references  =<ref name=Handbook >{{cite book |url=http://www.handbookofmineralogy.com/pdfs/chromite.pdf |title=Handbook of Mineralogy |chapter=Chromite |first1=John W. |last1=Anthony |first2=Richard A. |last2=Bideaux |first3=Kenneth W. |last3=Bladh |first4=Monte C. |last4=Nichols |page=122 |publisher=Mineralogical Society of America |access-date=13 April 2019 |archive-date=13 May 2021 |archive-url=https://web.archive.org/web/20210513182630/http://www.handbookofmineralogy.com/pdfs/chromite.pdf |url-status=dead }}</ref><ref name=Klein>{{cite book |last1=Klein |first1=Corneis |first2=Cornelius S. |last2=Hurlbut |title=Manual of Mineralogy |publisher=Wiley |edition=20th |pages=[https://archive.org/details/manualofmineralo00klei/page/312 312–313] |isbn=0471805807 |date=1985 |url-access=registration |url=https://archive.org/details/manualofmineralo00klei/page/312 }}</ref><ref name=Webmin >{{cite web|url=http://webmineral.com/data/Chromite.shtml |title=Chromite Mineral Data |work=Webmineral data |access-date=13 April 2019}}</ref><ref name=Mindat>{{cite web|url=http://www.mindat.org/min-1036.html |title=Chromite: Mineral information, data and localities |website=Mindat.org |author=Hudson Institute of Mineralogy |access-date=13 April 2019}}</ref>
}}
'''Chromite''' is a crystalline [[mineral]] composed primarily of [[iron(II) oxide]] and [[chromium(III) oxide]] compounds. It can be represented by the chemical formula of [[Iron|Fe]][[Chromium|Cr]]<sub>2</sub>[[Oxygen|O]]<sub>4</sub>. It is an [[oxide mineral]] belonging to the [[spinel group]]. The element [[magnesium]] can substitute for [[iron]] in variable amounts as it forms a [[solid solution]] with magnesiochromite ([[Magnesium|Mg]][[Chromium|Cr]]<sub>2</sub>[[Oxygen|O]]<sub>4</sub>).<ref>{{cite web|url=http://www.mindat.org/min-8675.html |title=Chromite-Magnesiochromite Series: Mineral information, data and localities |website=Mindat.org |author=Hudson Institute of Mineralogy |access-date=13 April 2019}}</ref> Substitution of the element [[aluminium]] can also occur, leading to [[hercynite]] ([[Iron|Fe]][[Aluminum|Al]]<sub>2</sub>[[Oxygen|O]]<sub>4</sub>).<ref>{{cite web|url=http://www.mindat.org/min-8674.html |title=Chromite-Hercynite Series: Mineral information, data and localities |website=Mindat.org |author=Hudson Institute of Mineralogy |access-date=13 April 2019}}</ref> Chromite today is mined particularly to make stainless steel through the production of [[ferrochrome]] ([[Iron|Fe]][[Chromium|Cr]]), which is an iron-chromium alloy.<ref>{{Cite web|url=https://miningwatch.ca/sites/default/files/chromite_review.pdf|title=Potential Toxic Effects of Chromium, Chromite Mining and Ferrochrome Production: A Literature Review|date=May 2012|access-date=March 15, 2019}}</ref>

Chromite grains are commonly found in large [[mafic]] igneous intrusions such as the [[Bushveld]] in South Africa and India. Chromite is iron-black in color with a metallic [[Lustre (mineralogy)|luster]], a dark brown [[Streak (mineralogy)|streak]] and a hardness on the [[Mohs scale of mineral hardness|Mohs]] scale of 5.5.<ref>{{Cite book|title=Dana's minerals and how to study them.|author=Hurlbut, Cornelius S.|date=1998|publisher=Wiley|author2=Sharp, W. Edwin|author3=Dana, Edward Salisbury|isbn=0471156779|edition=4th.|location=New York|oclc=36969745|url-access=registration|url=https://archive.org/details/danasmineralshow00hurl}}</ref> 
== Properties ==
Chromite minerals are mainly found in mafic-ultramafic [[Intrusive rock|igneous intrusions]] and are also sometimes found in [[metamorphic rock]]s. The chromite minerals occur in layered formations that can be hundreds of kilometres long and a few meters thick.<ref>{{Cite journal|last1=Latypov|first1=Rais|last2=Costin|first2=Gelu|last3=Chistyakova|first3=Sofya|last4=Hunt|first4=Emma J.|last5=Mukherjee|first5=Ria|last6=Naldrett|first6=Tony|date=2018-01-31|title=Platinum-bearing chromite layers are caused by pressure reduction during magma ascent|journal=Nature Communications|volume=9|issue=1|pages=462|doi=10.1038/s41467-017-02773-w|pmid=29386509|pmc=5792441|issn=2041-1723|bibcode=2018NatCo...9..462L}}</ref> Chromite is also common in [[iron meteorite]]s and form in association with [[silicate]]s and [[troilite]] minerals.<ref name="Fehr-2004">{{Cite journal|last1=Fehr|first1=Karl Thomas|last2=Carion|first2=Alain|s2cid=55658406|date=2004|title=Unusual large chromite crystals in the Saint Aubin iron meteorite|journal=Meteoritics & Planetary Science|volume=39|issue=S8|pages=A139–A141|doi=10.1111/j.1945-5100.2004.tb00349.x|issn=1086-9379|bibcode=2004M&PS...39..139F|doi-access=free}}</ref>

=== Crystal structure ===
The chemical composition of chromite can be represented as FeCr<sub>2</sub>O<sub>4</sub>, with the iron in the +2 [[oxidation state]] and the chromium in the +3 oxidation state.<ref name=Mindat /> [[Bauxite]], when presented as an [[ore]], or in massive form, forms as fine granular aggregates. The structure of the [[ore]] can be seen as platy, with breakages along planes of weakness. Chromite can also be presented in a thin section. The grains seen in thin sections are disseminated with crystals that are [[Euhedral and anhedral|euhedral]] to [[Euhedral and anhedral|subhedral]].<ref>{{Cite journal|last=Fortier|first=Y.|date=1941|title=Geology of Chromite|url=http://digitool.library.mcgill.ca/R/-?func=dbin-jump-full&amp;current_base=GEN01&amp;object_id=129707|journal=McGill University}}</ref>

Chromite contains Mg, ferrous iron [Fe(II)], Al and trace amounts of [[Titanium|Ti]].<ref name=Mindat /> Chromite can change into different minerals based on the amounts of each element in the mineral. Chromite is a part of the [[spinel group]], which means that it is able to form a complete [[solid solution]] series with other members in the same group. These include minerals such as chenmingite (FeCr<sub>2</sub>O<sub>4</sub>), [[xieite]] (FeCr<sub>2</sub>O<sub>4</sub>), magnesiochromite (MgCr<sub>2</sub>O<sub>4</sub>) and [[magnetite]] (Fe<sup>2+</sup>Fe<sup>3+</sup><sub>2</sub>O<sub>4</sub>). Chenmingite and xieite are [[Polymorphism (materials science)|polymorphs]] of chromite while magnesiochromite and magnetite are [[isostructural]] with chromite.<ref name="Mindat" />

=== Crystal size and morphology ===
Chromite occurs as massive and granular crystals and very rarely as [[Octahedron|octahedral]] crystals. [[Crystal twinning|Twinning]] for this mineral occurs on the {III} plane as described by the [[Crystal twinning#Common twin laws|spinel law]].<ref name=Mindat />

Grains of minerals are generally small in size. However, chromite grains up to 3&nbsp;cm have been found. These grains are seen to crystallize from the liquid of a [[meteorite]] body where there are low amounts of chromium and oxygen. The large grains are associated with stable [[Supersaturation|supersaturated]] conditions seen from the meteorite body.<ref name="Fehr-2004" />

=== Reactions ===
Chromite is an important mineral in helping to determine the conditions that rocks form. It can have reactions with various gases such as [[Carbon monoxide|CO]] and [[Carbon dioxide|CO<sub>2</sub>]]. The reaction between these gases and the solid chromite grains results in the reduction of the chromite and allows for the formation of iron and chromium [[alloy]]s. There could also be a formation of metal [[carbide]]s from the interaction with chromite and the gases.<ref>{{Citation|last=Eric|first=Rauf Hurman|chapter=Production of Ferroalloys|date=2014|pages=477–532|publisher=Elsevier|language=en|doi=10.1016/b978-0-08-096988-6.00005-5|isbn=9780080969886|title=Treatise on Process Metallurgy}}</ref>

Chromite is seen to form early in the [[crystallization]] process. This allows for chromite to be resistant to the alteration effects of high temperatures and pressures seen in the [[Metamorphic rock|metamorphic]] series. It is able to progress through the [[Metamorphic rock|metamorphic]] series unaltered. Other minerals with a lower resistance are seen to alter in this series to minerals such as [[Serpentine subgroup|serpentine]], [[biotite]] and [[garnet]].<ref>{{Cite web|url=https://www.galleries.com/minerals/oxides/chromite/chromite.htm|title=CHROMITE (Iron Chromium Oxide)|website=www.galleries.com |url-status=live |archive-url=https://web.archive.org/web/20111017013049/https://www.galleries.com/minerals/oxides/chromite/chromite.htm |archive-date=October 17, 2011 |access-date=2019-03-17}}</ref>

== Distribution of deposits ==
[[File:Yukon chromite prospect.jpg|thumb|left|A chromite prospect in [[Yukon]]. The black bands are chromite, which also carries [[platinum group metals]]. Gray rock is bleached [[ultramafic]]s.]]
Chromite is found as [[Cumulate rock|orthocumulate]] lenses in [[peridotite]] from the Earth's [[mantle (geology)|mantle]]. It also occurs in [[Layered intrusion|layered]], [[ultramafic]] intrusive rocks.<ref>{{cite journal | doi = 10.1016/0892-6875(88)90045-3 | title = Chromite- mineralogy and processing | year = 1988 | author = Gu, F | journal = Minerals Engineering | volume = 1 | pages = 235 | last2 = Wills | first2 = B | issue = 3| bibcode = 1988MiEng...1..235G }}</ref> In addition, it is found in metamorphic rocks such as some [[serpentinite]]s.  [[Ore]] deposits of chromite form as early magmatic differentiates. It is commonly associated with [[olivine]], [[magnetite]], [[Serpentine group|serpentine]] and [[corundum]].<ref>{{Cite journal|last1=Emeleus|first1=C. H.|last2=Troll|first2=V. R.|date=2014-08-01|title=The Rum Igneous Centre, Scotland|journal=Mineralogical Magazine|language=en|volume=78|issue=4|pages=805–839|doi=10.1180/minmag.2014.078.4.04|bibcode=2014MinM...78..805E|s2cid=129549874|issn=0026-461X|doi-access=free}}</ref> The vast [[Bushveld igneous complex|Bushveld Igneous Complex]] of [[South Africa]] is a large layered [[mafic]] to [[ultramafic]] [[Igneous rock|igneous]] body with some layers consisting of 90% chromite, forming the rare rock type [[chromitite]] (cf. chromite the mineral and chromitite, a rock containing chromite).<ref>Guilbert, John M., and Park, Charles F., Jr. (1986) ''The Geology of Ore Deposits,'' Freeman, {{ISBN|0-7167-1456-6}}</ref> The [[Stillwater igneous complex|Stillwater Igneous Complex]] in [[Montana]] also contains significant chromite.<ref name=Klein/>

Chromite suitable for commercial mining is found in just a handful of very substantial deposits. There are 2 main types of chromite deposits: [[Stratum|stratiform]] deposits and podiform deposits. Stratiform deposits in layered intrusions are the main source of chromite resources and are found in [[South Africa]], [[Canada]], [[Finland]], and [[Madagascar]]. Chromite resources from podiform deposits are mainly found in [[Kazakhstan]], [[Turkey]], and [[Albania]]. [[Zimbabwe]] is the only country that contains notable chromite reserves in both stratiform and podiform deposits.<ref name="Prasad-2016">{{Cite book|title=Environmental materials and waste: resource recovery and pollution prevention|editor=Prasad, M. N. V. |editor2=Shih, Kaimin|isbn=9780128039069|location=London|oclc=947118220|date=2016-04-19 }}</ref>

=== Stratiform deposits ===
Stratiform deposits are formed as large sheet-like bodies, usually formed in layered [[mafic]] to [[Ultramafic rock|ultramafic]] [[Igneous rock|igneous]] complexes. This type of deposit is used to obtain 98% of the worldwide chromite reserves.<ref name="Duke-1983">{{Cite book|title=Ore deposit models 7 : Magmatic Segregation Deposits of Chromite|author=Duke, J. M.|oclc=191989186}}</ref>

Stratiform deposits are typically seen to be of [[Precambrian]] in age and are found in [[craton]]s. The [[mafic]] to [[Ultramafic rock|ultramafic]] [[Igneous rock|igneous]] provinces that these deposits are formed in were likely intruded into [[continental crust]], which may have contained [[granite]]s or [[gneiss]]es. The shapes of these intrusions are described as tabular or funnel-shaped. The tabular intrusions were placed in the form of [[Sill (geology)|sills]] with the layering of these intrusions being parallel. Examples of these tabular intrusions can be seen in the [[Stillwater igneous complex|Stillwater Igneous Complex]] and [[Bird River greenstone belt|Bird River]]. The funnel-shaped intrusions are seen to be dipping towards the center of the intrusion. This gives the layers in this intrusion a [[syncline]] formation. Examples of this type of intrusion can be seen in the [[Bushveld Igneous Complex]] and the [[Great Dyke]].<ref name="Duke-1983" />

Chromite can be seen in stratiform deposits as multiple layers which consist of [[chromitite]]. Thicknesses for these layers range between 1&nbsp;cm and 1 m. Lateral depths can reach lengths of 70&nbsp;km. Chromitite is the main rock in these layers, with 50–95% of it being made of chromite and the rest being composed of [[olivine]], [[Pyroxene|orthopyroxene]], [[plagioclase]], [[Pyroxene|clinopyroxene]], and the various alteration products of these minerals. An indication of water in the magma is determined by the presence of brown [[mica]].<ref name="Duke-1983" />

=== Podiform deposits ===
Podiform deposits are seen to occur within the [[ophiolite]] sequences. The stratigraphy of the ophiolite sequence is deep-ocean sediments, [[pillow lava]]s, [[Sheeted dyke complex|sheeted dykes]], [[gabbro]]s and [[Ultramafic rock|ultramafic]] [[tectonite]]s.<ref name="Duke-1983" />

These deposits are found in ultramafic rocks, most notably in tectonites. It can be seen that the abundance of podiform deposits increase towards the top of the tectonites.<ref name="Duke-1983" />

Podiform deposits are irregular in shape. "Pod" is a term given by geologists to express the uncertain morphology of this deposit. This deposit shows [[Foliation (geology)|foliation]] that is parallel to the foliation of the host rock. Podiform deposits are described as discordant, subconcordant and concordant. Chromite in podiform deposits form as [[Euhedral and anhedral|anhedral]] grains. The ores seen in this type of deposit have nodular texture and are loosely-packed nodules with a size range of 5–20&nbsp;mm. Other minerals that are seen in podiform deposits are [[olivine]], [[Pyroxene|orthopyroxene]], [[Pyroxene|clinopyroxene]], [[pargasite]], [[Mica|Na-mica]], [[albite]], and [[jadeite]].<ref name="Duke-1983" />

== Health and environmental impacts ==
Chromium extracted from chromite is used on a large scale in many industries, including metallurgy, electroplating, paints, tanning, and paper production. Environmental contamination with hexavalent chromium is a major health and environmental concern. Chromium is most stable in its [[trivalent]] (Cr(III)) form, seen in stable compounds such as natural ores. Cr(III) is an essential nutrient, required for [[lipid]] and [[glucose]] metabolism in animals and humans. In contrast, the second most stable form, [[hexavalent]] chromium (Cr(VI)), is generally produced through human activity and rarely seen in nature (as in [[crocoite]]), and is a highly toxic carcinogen that may kill animals and humans if ingested in large doses.<ref>{{Cite journal|last1=Zayed|first1=Adel M.|last2=Terry|first2=Norman|date=2003-02-01|title=Chromium in the environment: factors affecting biological remediation|url=https://doi.org/10.1023/A:1022504826342|journal=Plant and Soil|language=en|volume=249|issue=1|pages=139–156|doi=10.1023/A:1022504826342|bibcode=2003PlSoi.249..139Z |s2cid=34502288|issn=1573-5036|url-access=subscription}}</ref>

'''Health effects'''

When chromite [[ore]] is mined, it is aimed for the production of [[ferrochrome]] and produces a chromite [[concentrate]] of a high chromium to iron ratio.<ref>{{Cite journal|last1=Kanari|first1=Ndue|last2=Allain|first2=Eric|last3=Filippov|first3=Lev|last4=Shallari|first4=Seit|last5=Diot|first5=Frédéric|last6=Patisson|first6=Fabrice|date=2020-10-09|title=Reactivity of Low-Grade Chromite Concentrates towards Chlorinating Atmospheres|journal=Materials|volume=13|issue=20|page=4470|doi=10.3390/ma13204470|issn=1996-1944|pmc=7601304|pmid=33050262|bibcode=2020Mate...13.4470K|doi-access=free}}</ref> It can also be crushed and processed. Chromite concentrate, when combined with a [[Reducing agent|reductant]] such as [[coal]] or [[Coke (fuel)|coke]] and a high temperature furnace can produce [[ferrochrome]]. Ferrochrome is a type of [[ferroalloy]] that is an [[alloy]] in between chromium and iron. This ferroalloy, as well as chromite [[concentrate]] can introduce various health effects. Introducing a definitive control approach and distinct mitigation techniques can provide importance related to the safety of human health.<ref>Ontario Agency for Health Protection and Promotion (Public Health Ontario), Kim JH, Copes R. Case Study: Chromite mining and health concerns. Toronto, ON: Queen’s Printer for Ontario; 2015. https://www.publichealthontario.ca/-/media/documents/c/2015/case-study-chromite-mining.pdf?la=en</ref>

When chromite ore is exposed to surface conditions, [[weathering]] and [[redox|oxidation]] can occur. The element chromium is most abundant in chromite in the form of trivalent (Cr-III). When chromite [[ore]] is exposed to aboveground conditions, Cr-III can be converted to [[Hexavalent chromium|Cr-VI]], which is the hexavalent state of chromium. Cr-VI is produced from Cr-III by means of dry [[Milling (machining)|milling]] or grinding of the ore. This is due to the moistness of the milling process as well as the [[atmosphere]] in which the milling is taking place. A wet environment and a non-oxygenated atmosphere are ideal conditions to produce less Cr-VI, while the opposite is known to create more Cr-VI.<ref name="MiningWatch-2012">''Potential Toxic Effects of Chromium, Chromite Mining and Ferrochrome Production : A Literature Review''. MiningWatch Canada. 2012 (PDF). May 2012.https://miningwatch.ca/sites/default/files/chromite_review.pdf</ref>

Production of [[ferrochrome]] is observed to emit [[pollutant]]s into the air such as [[nitrogen oxide]]s, [[Oxocarbon|carbon oxides]] and [[Sulfur oxide|sulfur oxides]], as well as dust [[particulates]] with a high concentration of [[heavy metals]] such as [[chromium]], [[zinc]], [[lead]], [[nickel]] and [[cadmium]]. During high temperature [[smelting]] of chromite [[ore]] to produce [[Ferrochrome]], Cr-III is converted to Cr-VI. As with chromite ore, Ferrochrome is [[Milling (grinding)|milled]] and therefore produces Cr-VI. Cr-VI is therefore introduced into the dust when the [[Ferrochrome]] is produced. This introduces health risks such as inhalation potential and [[wiktionary:Special:Search/leaching|leaching]] of toxins into the environment. Human exposure to chromium is ingestion, skin contact, and inhalation. Chromium-III and VI will accumulate in the tissues of humans and animals. The excretion of this type of chromium from the body tends to be very slow which means that elevated concentrations of chromium can be seen decades later in human tissues.<ref name="MiningWatch-2012" />

'''Environmental effects'''

Chromite mining, chromium, and ferrochrome production can be toxic for the environment.<ref name="MiningWatch-2012" /> Chromite [[mining]] is necessary when it comes to the production of economic [[Commodity|commodities]].<ref>Das, P.K., Das, B.P. & Dash, P. Chromite mining pollution, environmental impact, toxicity and phytoremediation: a review. ''Environ Chem Lett'' (2020). https://doi.org/10.1007/s10311-020-01102-w</ref>

As a result of leaching of soils and the explicit discharge from industrial activities, [[weathering]] of rocks that contain chromium will enter the water column. The route of chromium uptake in plants is still ambiguous, but because it is a nonessential element, chromium will not have a distinct mechanism for that uptake which is independent from chromium speciation.<ref name="Oliveira-2012">{{Cite journal|last=Oliveira|first=Helena|date=2012-05-20|title=Chromium as an Environmental Pollutant: Insights on Induced Plant Toxicity|journal=Journal of Botany|volume=2012|pages=1–8|doi=10.1155/2012/375843|language=en|doi-access=free}}</ref> Plant studies have shown that toxic effects on plants from chromium include things such as wilting, narrow leaves, delayed or reduced growth, a decrease in [[chlorophyll]] production, damage to root membranes, small root systems, death and many more.<ref name="MiningWatch-2012" /> Chromium's structure is similar to other essential elements which means that it can impact the mineral nutrition of plants.<ref name="Oliveira-2012" />
[[File:Chromitite Bushveld South Africa.jpg|thumb|Bushveld Chromite]]
During industrial activities and production things such as sediment, water, soil, and air all become polluted and contaminated with chromium. Hexavalent chromium has negative impacts towards soil ecology because it decreases soil micro-organism presence, function, and diversity.<ref name="MiningWatch-2012" /> Chromium concentrations in soil diversify depending on the different compositions of the sediments and rocks that the soil is made from. The chromium present in soil is a mixture of both Cr(VI) and Cr(III).<ref name="Oliveira-2012" /> Certain types of chromium such as [[Chromium VI|Chromium-VI]] has the capability to pass into the cells of organisms. Dust particles from industry operations and industrial wastewater contaminate and pollute surface water, groundwater, and soils.<ref name="MiningWatch-2012" />

In aquatic environments, chromium could experience things such as [[dissolution (chemistry)|dissolution]], [[sorption]], [[precipitation]], [[oxidation]], [[Reduction (chemistry)|reduction]], and [[desorption]].<ref name="Oliveira-2012" /> In aquatic ecosystems chromium [[Bioaccumulation|bioaccumulates]] in invertebrates, aquatic plants, fish, and algae. These toxic effects will operate differently because things such as sex, size, and the development stage of an organism may vary. Things such as the temperature of the water, its alkalinity, salinity, pH, and other contaminants will also impact these toxic effects on organisms.<ref name="MiningWatch-2012" />

[[File:Chromitite band in chromitic serpentinite (early Neoarchean; North Star Mine, near eroded edge of Hellroaring Plateau, Red Lodge Chromite District, Beartooth Mountains, southern Montana, USA) (15188887016).jpg|thumb|Chromitite band in chromitic serpentinite]]

== Applications ==
Chromite can be used as a [[refractory]] material because it has a high [[Thermostability|heat stability]].<ref>{{cite book | url = https://books.google.com/books?id=0ugkNtlWKWEC&pg=PA205 | title = Pocket Manual Refractory Materials: Structure - Properties - Verification | first = Gerald | last = Routschka | publisher = Vulkan-Verlag  | year = 2008 | isbn = 978-3-8027-3158-7}}</ref> The chromium extracted from chromite is used in [[chrome plating]] and alloying for production of corrosion resistant [[superalloy]]s, [[nichrome]], and [[stainless steel]]. <ref name="Geology-2021">{{Cite web |title=Uses of Chromium {{!}} Supply, Demand, Production, Resources |url=https://geology.com/usgs/uses-of-chromium/ |access-date=2021-03-25 |website=geology.com}}</ref> Chromium is used as a [[pigment]] for glass, glazes, and paint, and as an [[oxidizing agent]] for tanning leather.<ref>{{cite web |url=http://www.mineralszone.com/minerals/chromite.html |title=Chromite Mineral, Iron Chromium Oxide, Chromite Uses, Chromium Oxide Properties |url-status=dead |archive-url=https://web.archive.org/web/20170108113638/http://www.mineralszone.com/minerals/chromite.html |archive-date=8 January 2017 |access-date=21 March 2014 }}</ref> It is also sometimes used as a [[gemstone]].<ref>Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens, p.189</ref> Most shiny car trim is chromium plated. Superalloys that contain chromium allow jet engines to run under high stress, in a chemically oxidizing environment, and in high-temperature situations.<ref name="Geology-2021" />

=== Porcelain tile pigmentation ===
[[Porcelain tile]]s are often produced with many different colours and [[pigment]]ations. The usual contributor to colour in fast-fired porcelain tiles is black {{chem|(Fe||,Cr)|2|O|3}} pigment, which is fairly expensive and is [[Chemical synthesis|synthetic]]. Natural chromite allows for an inexpensive and inorganic pigmentation alternative to the expensive {{chem|(Fe|,Cr)|2|O|3}} and allows for the [[microstructure]] and mechanical properties of the tiles to not be substantially altered or modified when introduced.<ref>{{Citation|last1=Bondioli|first1=Federica|chapter=Chromite as a Pigment for Fast-Fired Porcelain Tiles|pages=44–58|publisher=John Wiley & Sons|isbn=9780470294420|last2=Ferrari|first2=Anna Maria|last3=Leonelli|first3=Cristina|last4=Manfredini|first4=Tiziano|doi=10.1002/9780470294420.ch6|title=98th Annual Meeting and the Ceramic Manufacturing Council's Workshop and Exposition: Materials & Equipment/Whitewares: Ceramic Engineering and Science Proceedings, Volume 18, Issue 2|volume=18|year=1997|hdl=11380/448364}}</ref>

== Gallery ==
<gallery widths="165" heights="165">
File:Chromite by petrographic microscope.jpg|Chromite sample under a [[petrographic microscope]] in plain polarized light (PPL)
File:Chromite calcite uvarovit.jpg|Chromite grains with white [[calcite]] grains
File:Chromite-pas-63b.jpg|Green [[oxide]] of chromium from [[Baltimore]], [[Maryland]]
File:Chromite-468934.jpg|Large, equant chromite crystals from Hangha, [[Kenema District]], Eastern Province, [[Sierra Leone]]
</gallery>

== See also ==
* [[Alloy steel]]
* [[Reduction potential]]
* [[Ring of Fire (Northern Ontario)]]

== References ==
{{Reflist}}

==External links==
{{Commons category|Chromite}}
* [http://www.minerals.net/mineral/oxides/chromite/chromite.htm Minerals.net]
* [http://minerals.usgs.gov/minerals/pubs/country/1998/9324098.pdf USGS info.]

{{Ores}}

{{Authority control}}

[[Category:Chromium minerals]]
[[Category:Cubic minerals]]
[[Category:Minerals in space group 227]]
[[Category:Iron(II) minerals]]
[[Category:Magnesium minerals]]
[[Category:Spinel group]]<!--Please keep this redundant category as it has several uses outside of being a gemstone-->
[[Category:Spinel gemstones]]
[[Category:Refractory materials]]