claudetite

{{Infobox mineral | name = Claudetite | category = Oxide minerals | boxwidth = | boxbgcolor = | image = Claudetite-700910.jpg | caption = | formula = As2 O3 | IMAsymbol = Ctd | molweight = | strunz = 4.CB.45 | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/n | unit cell = a = 5.33 Å, b = 12.98 Å, c = 4.54 Å; β = 94.27°; Z = 4 | color = Colorless to white | habit = Thin tabular crystals, fibrous crusts | twinning = Contact or penetration on {100} | cleavage = Perfect on {010} micaceous | fracture = Splintery | tenacity = Flexible | mohs = 2.15 | luster = Vitreous, pearly on cleavage surfaces | refractive = nα = 1.870 nβ = 1.920 nγ = 2.010 | opticalprop = Biaxial (−) | birefringence = δ = 0.140 | 2V = 58° (measured) | pleochroism = | streak = | gravity = 4.14–4.15 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = }} thumb Claudetite is an arsenic oxide mineral with chemical formula As2O3. Claudetite is formed as an oxidation product of arsenic sulfides and is colorless or white. It can be associated with arsenolite (the cubic form of As2O3) as well as realgar (As4S4), orpiment (As2S3) and native sulfur.

It was first described in 1868 for an occurrence in the San Domingo mines, Algarve, Portugal. It was first described by and named for the French chemist Frederick Claudet.