Arsenolite

Arsenolite
Arsenolite from the White Caps Mine, Manhattan District, Nye County, Nevada (size: 6.0 x 4.3 x 2.9 cm)
General
Category	Oxide mineral
Formula (repeating unit)	As4O6
IMA symbol	Aso
Strunz classification	4.CB.50
Crystal system	Cubic
Crystal class	Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group	Fd3m
Unit cell	a = 11.074 Å; Z = 16
Identification
Formula mass	197.841 g/mol
Color	White, pale blue, pink to pale yellow if impure
Crystal habit	Common as tiny octahedra; aggregates or crusts; botryoidal, stalactitic
Cleavage	On {111}
Fracture	Conchoidal
Mohs scale hardness	1.5
Luster	Vitreous to silky; may be earthy or dull
Streak	white /pale white
Diaphaneity	Transparent
Specific gravity	3.87
Optical properties	Isotropic; may be anomalously anisotropic
Refractive index	n = 1.755
Other characteristics	Astringent, sweetish taste; toxic
References

Arsenolite is an arsenic mineral, chemical formula As₄O₆. It is formed as an oxidation product of arsenic sulfides. Commonly found as small octahedra it is white, but impurities of realgar or orpiment may give it a pink or yellow hue. It can be associated with its dimorph claudetite (a monoclinic form of As₂O₃) as well as realgar (As₄S₄), orpiment (As₂S₃) and erythrite, Co₃(AsO₄)₂·8H₂O.

Arsenolite belongs to the minerals which are highly toxic.

Occurrence

It was first described in 1854 for an occurrence in the St Andreasberg District, Harz Mountains, Lower Saxony, Germany.

It occurs by the oxidation of arsenic-bearing sulfides in hydrothermal veins. It also occurs as a result of mine or coal seam fires.