Hemihedrite

{{Short description|Rare lead zinc chromate silicate mineral}} {{infobox mineral | name = Hemihedrite | image = Hemihedrite-phoenicochroite-537207.jpg | imagesize = 260px | alt = | caption = Red phoenicochroite and orange hemihedrite microcrystals richly cover the matrix | category = Chromate mineral | formula = Pb10Zn(CrO4)6(SiO4)2(F,OH)2 | IMAsymbol = Hhe<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> | molweight = | strunz = 7.FC.15 | dana = | system = Triclinic | symmetry = P{{overline|1}} (No. 2) | unit cell = a = 9.49, b = 11.44 c = 10.84 [Å]; α = 120.5° β = 92.1°, γ = 55.83°; Z = 1 | color = Bright orange, henna-brown, to almost black | colour = | habit = Euhedral crystals with hemihedral morphology | twinning = Present | cleavage = | fracture = | tenacity = | mohs = 3 | luster = Vitreous | streak = Saffron-yellow | diaphaneity = Translucent to transparent | gravity = 6.42 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 2.105 nβ = 2.320 nγ = 2.650 | birefringence = δ = 0.545 | pleochroism = Feeble, yellow to orange | 2V = 88° (measured) | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref name=HBM>[http://rruff.info/doclib/hom/hemihedrite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-1859.html Hemihedrite on Mindat.org]</ref><ref name=Webmin>[http://www.webmineral.com/data/Hemihedrite.shtml Hemihedrite data on Webmineral]</ref><ref name=atlas>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Hemihedrite Mineralienatlas]</ref><ref>{{cite journal |last1=McLean |first1=W.J. |last2=Anthony |first2=J.W. |journal=American Mineralogist |volume=55 |year=1970 |pages=1103–1114 |title=The crystal structure of hemihedrite}}</ref> }} '''Hemihedrite''' is a rare lead zinc chromate silicate mineral with formula Pb10Zn(CrO4)6(SiO4)2(F,OH)2. It forms a series with the copper analogue iranite.<ref name=Mindat/>

==Discovery and occurrence== Hemihedrite was first described in 1967 for occurrences in the Florence lead silver mine in the Ripsey District, Tortilla Mountains, Pinal County, Arizona, US.<ref name=Mindat/> It was named for the hemihedral morphology of its crystals.<ref name=HBM/>

It occurs in oxidized veins containing galena, sphalerite and pyrite. Associated secondary minerals include cerussite, phoenicochroite, vauquelinite, willemite, wulfenite, galena, sphalerite, pyrite, tennantite and chalcopyrite.<ref name=HBM/> It has been reported from several mining districts in Arizona and one in Nevada. It has also been reported from the Antofagasta Region of Chile and the Anarak District of Esfahan Province, Iran.<ref name=Mindat/>

==References== {{reflist}}

Category:Chromate minerals Category:Triclinic minerals Category:Lead minerals Category:Zinc minerals Category:Minerals in space group 2 Category:Minerals described in 1967