{{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 | 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 | class = Hexoctahedral (m{{overline|3}}m) <br/>H-M symbol: (4/m {{overline|3}} 2/m) | symmetry = ''F''m{{overline|3}}m | unit cell = a = 5.69 Å; Z = 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 magnesium 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, but typically occurs as anhedral grains between other minerals.
==Discovery and occurrence== It was first described in 1862 for an occurrence in the Bustee meteorite, Gorakhpur, Uttar Pradesh, India. It was named for Irish geologist 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 minerals in enstatite chondrite and achondrite meteorites.<ref name=HBM/><ref name=Webmin/> It occurs in association with enstatite, augite, niningerite, osbornite, troilite, gypsum and calcite.<ref name=HBM/> It has been reported from a variety of meteorite locations around the world including the Allan Hills 84001 meteorite of Antarctica. It has also been reported from a slag occurrence in France and a coal deposit in Poland.<ref name=Mindat/>
==See also== * 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}}