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Brassite

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Brassite
Brassite (white) accompanied by rösslerite
General
CategoryArsenate mineral
Formula
(repeating unit)
Mg(AsO3OH)·4(H2O)
IMA symbolBsi[1]
Strunz classification8.CE.15
Dana classification39.01.07.01
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPbca
Unit cella = 7.472 Å,
b = 10.891 Å,
c = 16.585 Å; Z = 8
Identification
ColorWhite
Crystal habitCryptocrystalline crusts
Cleavage{001} Perfect
FractureIrregular/uneven, splintery
TenacityBrittle
LusterSilky, dull, earthy
StreakWhite
DiaphaneityTranslucent
Specific gravity2.28
Optical propertiesBiaxial (+)
Refractive indexnα = 1.531 nβ = 1.546 nγ = 1.562
Birefringence0.031
PleochroismNon-pleochroic
2V angle80°
Dispersionr < v moderate
Solubility+++ HCl, + H2O
References[2][3][4][5]

Brassite is a rare arsenate mineral with the chemical formula Mg(AsO3OH)·4(H2O). It was named brassite, in 1973, to honor French chemist Réjane Brasse, who first synthesized the compound. The type locality for brassite is Jáchymov of the Czech Republic.[3]

It occurs as an alteration of magnesium carbonate minerals by arsenic bearing solutions. It occurs associated with pharmacolite, picropharmacolite, weilite, haidingerite, rauenthalite, native arsenic, realgar and dolomite.[4]

Localities

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Czech Republic:

France:

Germany:

  • Wilhelm Mine (Wechselschacht), Bauhaus, Richelsdorf District, Hesse, Germany
  • Ore dumps, Richelsdorf Smelter, Süss, Richelsdorf District, Hesse, Germany

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Webmineral.com - Brassite
  3. ^ a b Mindat.org - Brassite
  4. ^ a b "Handbook of Mineralogy - Brassite" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2013-01-25.
  5. ^ Mineralatlas.com - Brassite