arsenoclasite

{{Infobox mineral | name = Arsenoclasite | category = Arsenate mineral | image = | caption = | formula = Mn5(AsO4)2(OH)4 |IMAsymbol=Asc | molweight = 620.56 g/mol | strunz = 8.BD.10 | dana = 41.4.1.1 | system = Orthorhombic | class = Disphenoidal (222) H-M symbol: (222) | symmetry = P212121 | unit cell = a = 9.31, b = 5.75 c = 18.29 [Å]; Z = 4 | color = Red, dark orange-brown | habit = Massive or granular | twinning = | cleavage = Perfect on {010} | fracture = | tenacity = | mohs = 5–6 | luster = | polish = | refractive = nα = 1.787, nβ = 1.810, nγ = 1.816 | opticalprop = Biaxial (−) | birefringence = δ = 0.029 | 2V = 53° | dispersion = Extreme | pleochroism = | fluorescence= | absorption = | streak = | gravity = | density = 4.16 g/cm3 (measured) | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Translucent | other = | references = }} Arsenoclasite (originally arsenoklasite) is a red or dark orange brown mineral with formula Mn5(AsO4)2(OH)4. The name comes from the Greek words αρσενικόν (for arsenic) and κλάσις (for cleavage), as arsenoclasite contains arsenic and has perfect cleavage. The mineral was discovered in 1931 in Långban, Sweden.

==Description== Arsenoclasite is red or dark orange brown in color. The mineral rarely occurs as crystals; rather it has either a massive or granular habit. When crystals are present, they are no larger than . Arsenoclasite has been found in association with adelite, allactite, barite, calcite, dolomite, gatehouseite, hausmannite, hematite, manganoan ferroan calcite, sarkinite, and shigaite. The mineral occurs in fissures of metamorphosed Fe-Mn ore bodies and sedimentary Fe-Mn deposits.