# Hemihedrite

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> Source: https://en.wikipedia.org/wiki/Hemihedrite
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{{Short description|Rare lead zinc chromate silicate mineral}}
{{infobox mineral
| name        = Hemihedrite
| image       = Hemihedrite-phoenicochroite-537207.jpg
| imagesize   = 260px
| alt         = 
| caption     = Red [phoenicochroite](/source/phoenicochroite) and orange hemihedrite microcrystals richly cover the matrix
| category    = [Chromate mineral](/source/%3ACategory%3Achromate_minerals)
| formula     = Pb<sub>10</sub>Zn(CrO<sub>4</sub>)<sub>6</sub>(SiO<sub>4</sub>)<sub>2</sub>(F,OH)<sub>2</sub>
| 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](/source/Triclinic)
| symmetry    = P{{overline|1}}  (No. 2)
| unit cell   = a = 9.49, b = 11.44 <br/>c = 10.84&nbsp;[Å]; α = 120.5° <br/>β = 92.1°, γ = 55.83°; Z&nbsp;=&nbsp;1
| color       = Bright orange, henna-brown, to almost black
| colour      = 
| habit       = Euhedral crystals with [hemihedral](/source/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  = n<sub>α</sub> = 2.105 n<sub>β</sub> = 2.320 n<sub>γ</sub> = 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](/source/lead) [zinc](/source/zinc) [chromate](/source/Chromate_ion) [silicate mineral](/source/silicate_mineral) with formula Pb<sub>10</sub>Zn(CrO<sub>4</sub>)<sub>6</sub>(SiO<sub>4</sub>)<sub>2</sub>(F,OH)<sub>2</sub>. It forms a series with the copper analogue [iranite](/source/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](/source/Tortilla_Mountains), [Pinal County, Arizona](/source/Pinal_County%2C_Arizona), US.<ref name=Mindat/> It was named for the hemihedral morphology of its crystals.<ref name=HBM/>

It occurs in [oxidized](/source/Redox) [veins](/source/Vein_(geology)) containing [galena](/source/galena), [sphalerite](/source/sphalerite) and [pyrite](/source/pyrite). Associated secondary minerals include [cerussite](/source/cerussite), [phoenicochroite](/source/phoenicochroite), [vauquelinite](/source/vauquelinite), [willemite](/source/willemite), [wulfenite](/source/wulfenite), galena, sphalerite, pyrite, [tennantite](/source/tennantite) and [chalcopyrite](/source/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](/source/Antofagasta_Region) of [Chile](/source/Chile) and the Anarak District of [Esfahan Province](/source/Esfahan_Province), [Iran](/source/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

{{silicate-mineral-stub}}

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