Arsenolite (Size: 6.0 x 4.3 x 2.9 cm) Locality: White Caps Mine, Manhattan , Manhattan District , Nye County , Nevada , USA ( Locality at mindat.org ) Arsenolite is an uncommon arsenic oxide, formed as an oxidation product of arsenic-bearing sulphides in hydrothermal veins. Highly lustrous and translucent, yellow-green and colorless octahedrons are festooned on the sulfide matrix on this very rich and showy piece from the famous White Caps Mine at Manhattan, Nevada. The White Caps produced the finest USA stibnites. Old-time, very high quality and rich material. Ex. Howard Belsky Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Arsenolite
The oxide of arsenic, formed where arsenic sulfides break down — usually tiny white octahedra, sometimes tinted by realgar or orpiment.
Intro adapted from Wikipedia (CC BY-SA).
Arsenolite is an IMA-recognized mineral species in the arsenate class, with the chemical formula As₂O₃.
It crystallizes in the cubic crystal system (space group Fd3m). It is a member of the Arsenolite structural group.
Key properties: Mohs hardness 1.5; specific gravity 3.87; White to pale yellowish white streak; Vitreous to silky luster; refractive index 1.755.
IMA symbol Aso, grandfathered status — known before the IMA’s founding, named in 1854.
An oxidation product of other arsenic-bearing sulfides in hydrothermal veins; may be formed in mine fires or in burning coal seams.
It is found associated with Claudetite, realgar, orpiment, erythrite.
The name refers to ARSENic in the composition.