# Oldhamite

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Oldhamite
> Markdown URL: https://mediated.wiki/source/Oldhamite.md
> Source: https://en.wikipedia.org/wiki/Oldhamite
> Source revision: 1276328855
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Rocksalt group, sulfide mineral}}
{{infobox mineral
| name        = Oldhamite
| boxwidth    = 
| boxbgcolor  = 
| image       = Oldhamite-510145.jpg
| imagesize   = 
| alt         = 
| caption     = Oldhamite (field of view: 1.5 cm)
| category    = [Sulfide mineral](/source/Sulfide_mineral)
| formula     = {{chem2|(Ca,Mg)S}}
| IMAsymbol   = Old<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      = 2.CD.10
| dana        = 
| system      = [Cubic](/source/Cubic_crystal_system)
| class       = Hexoctahedral (m{{overline|3}}m) <br/>[H-M symbol](/source/H-M_symbol): (4/m {{overline|3}} 2/m)
| symmetry    = ''F''m{{overline|3}}m
| unit cell   = a = 5.69&nbsp;Å; Z&nbsp;=&nbsp;4
| color       = Pale chestnut-brown
| habit       = Crystal nodules, anhedral grains
| twinning    = 
| cleavage    = Good on {001}
| fracture    = 
| tenacity    = 
| mohs        = 4
| luster      = Sub-metallic
| streak      = 
| diaphaneity = Transparent
| gravity     = 2.58
| density     = 
| polish      = 
| opticalprop = Isotropic
| refractive  = n = 2.137
| birefringence = 
| pleochroism = 
| 2V          = 
| dispersion  = 
| extinction  = 
| length fast/slow =
| fluorescence = 
| absorption  = 
| melt        = 
| fusibility  = 2450 °C
| diagnostic  = 
| solubility  = 
| impurities  = 
| alteration  = Tarnishes on exposure to moist air
| other       = 
| prop1       = 
| prop1text   =
|references   = <ref name=HBM>[https://www.handbookofmineralogy.org/pdfs/oldhamite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-2970.html Oldhamite on Mindat.org]</ref><ref name=Webmin>[http://webmineral.com/data/Oldhamite.shtml Webmineral dat for oldhamite]</ref>
}}
'''Oldhamite''' is a [calcium](/source/calcium) [magnesium](/source/magnesium) [sulfide mineral](/source/sulfide_mineral) with the chemical formula {{chem2|(Ca,Mg)S}}.<ref name=HBM/><ref name=Mindat/> Ferrous iron may also be present in the mineral resulting in the chemical formula {{chem2|(Ca,Mg,Fe)S}}.<ref name=Webmin/> It is a pale to dark brown accessory mineral in meteorites. It crystallizes in the [cubic crystal system](/source/cubic_crystal_system), but typically occurs as [anhedral](/source/Euhedral_and_anhedral) grains between other minerals.

==Discovery and occurrence==
It was first described in 1862 for an occurrence in the [Bustee meteorite](/source/Bustee_meteorite), [Gorakhpur](/source/Gorakhpur), [Uttar Pradesh](/source/Uttar_Pradesh), [India](/source/India). It was named for Irish geologist [Thomas Oldham](/source/Thomas_Oldham) (1816–1878), the Director of the Indian Geological Survey.<ref name=HBM/><ref name=Mindat/>

It occurs as an interstitial mineral phase between [silicate mineral](/source/silicate_mineral)s in [enstatite chondrite](/source/enstatite_chondrite) and [achondrite](/source/achondrite) [meteorite](/source/meteorite)s.<ref name=HBM/><ref name=Webmin/> It occurs in association  with [enstatite](/source/enstatite), [augite](/source/augite), [niningerite](/source/niningerite), [osbornite](/source/osbornite), [troilite](/source/troilite), [gypsum](/source/gypsum) and [calcite](/source/calcite).<ref name=HBM/> It has been reported from a variety of meteorite locations around the world including the [Allan Hills 84001](/source/Allan_Hills_84001) meteorite of [Antarctica](/source/Antarctica). It has also been reported from a [slag](/source/slag) occurrence in France and a coal deposit in Poland.<ref name=Mindat/>

==See also==
* [Glossary of meteoritics](/source/Glossary_of_meteoritics)
 
==References==
{{Reflist}}

{{Meteorites}}

Category:Meteorite minerals
Category:Sulfide minerals
Category:Cubic minerals
Category:Minerals in space group 225
Category:Galena group

{{sulfide-mineral-stub}}

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