# Cohenite

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> Markdown URL: https://mediated.wiki/source/Cohenite.md
> Source: https://en.wikipedia.org/wiki/Cohenite
> Source revision: 1242863482
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{{Short description|Iron carbide mineral}}
{{Infobox mineral
| name        = Cohenite
| category    = Native element mineral, carbide
| boxwidth    = 
| boxbgcolor  = 
| image       = Kristallstruktur Zementit.png
| imagesize   = 
| caption     = Structure of cohenite (or cementite)
| formula     = ([Fe](/source/Iron),[Ni](/source/Nickel),[Co](/source/Cobalt))<sub>3</sub>[C](/source/Carbon)
| IMAsymbol=Coh<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      = 1.BA.05
| system      = [Orthorhombic](/source/Orthorhombic)
| class       = Dipyramidal (mmm) <br/>[H-M symbol](/source/H-M_symbol): (2/m 2/m 2/m)
| symmetry    = ''Pnma''
| unit cell   = a = 5.09&nbsp;Å, b = 6.74&nbsp;Å, <br/>c = 4.52&nbsp;Å; Z&nbsp;=&nbsp;4
| color       = Tin-white; oxidizes to light bronze then golden yellow
| habit       = Platy to needlelike crystals; also as rims on or in dendritic intergrowths with iron
| twinning    = 
| cleavage    = Good on {100}, {010}, and {001}
| fracture    = 
| tenacity    = Brittle
| mohs        = 5.5–6
| luster      = Metallic
| polish      = 
| refractive  = 
| opticalprop = 
| birefringence = 
| dispersion  = 
| pleochroism = 
| fluorescence= 
| absorption  = 
| streak      = 
| gravity     = 7.2–7.65
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Opaque
| other       = Strongly magnetic
| references  = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Cementit Mineralienatlas]</ref><ref name=Mindat>[http://www.mindat.org/min-1107.html Mindat.org Cohenite]</ref><ref name=Webmin>[http://www.webmineral.com/data/Cohenite.shtml Webmineral.com Cohenite]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/cohenite.pdf Handbook of Mineralogy]</ref>
}}

'''Cohenite''' is a naturally occurring [iron](/source/iron) [carbide](/source/carbide) [mineral](/source/mineral) with the chemical structure ([Fe](/source/Iron), [Ni](/source/Nickel), [Co](/source/Cobalt))<sub>3</sub>[C](/source/Carbon). This forms a hard, shiny, silver mineral which was named by E. Weinschenk in 1889 after the German mineralogist [Emil Cohen](/source/Emil_Cohen), who first described and analysed material from the Magura meteorite found near [Slanica](/source/Slanica), [Žilina Region](/source/%C5%BDilina_Region), [Slovakia](/source/Slovakia).<ref name=Mindat/> Cohenite is found in rod-like crystals in [iron meteorite](/source/iron_meteorite)s.<ref>Vagn F. Buchwald, ''Handbook of Iron Meteorites,'' University of California Press, 1975 {{ISBN|978-0520029347}}</ref> 

On Earth cohenite is stable only in rocks which formed in a strongly [reducing](/source/Redox) environment and contain [native iron](/source/native_iron) deposits. Such conditions existed in some places where molten [magma](/source/magma)s invaded [coal](/source/coal) deposits, e.g. on [Disko Island](/source/Disko_Island) in [Greenland](/source/Greenland), or at the [Bühl](/source/B%C3%BChl_(Baden)) near [Kassel](/source/Kassel) in [Germany](/source/Germany).<ref name=HBM/>

Associated minerals include native iron, [schreibersite](/source/schreibersite), [troilite](/source/troilite) and [wüstite](/source/w%C3%BCstite).<ref name=HBM/>

Similar iron carbides occur also in technical iron alloys and are called [cementite](/source/cementite).

==See also==
*[Edscottite](/source/Edscottite)
* [Glossary of meteoritics](/source/Glossary_of_meteoritics)
*[List of minerals](/source/List_of_minerals)
*[List of minerals named after people](/source/List_of_minerals_named_after_people)

== References ==
{{Reflist}}

{{Meteorites}}

Category:Carbide minerals
Category:Iron minerals
Category:Meteorite minerals
Category:Orthorhombic minerals
Category:Minerals in space group 62
Category:Native element minerals

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Adapted from the Wikipedia article [Cohenite](https://en.wikipedia.org/wiki/Cohenite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Cohenite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.