3.8 x 3.6 x 2.7 cm. A great rarity from California from the collection of Paolo Matioli featuring micro glassy crystals of the arsenic oxide, claudetite which is the monoclinic dimorph of arsenolite. The species was discovered in 1868, was named after F. Claudet, a French chemist. The label on this specimen states that micro orpiment, pararealgar and realgar are present as well. Likely from the Unnamed S prospect, 4-S Ranch area, Imperial Co., California, USA. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Claudetite
The monoclinic form of arsenic trioxide — a colorless secondary mineral of oxidizing arsenic sulfides, companion to arsenolite, realgar and orpiment.
Intro adapted from Wikipedia (CC BY-SA).
Claudetite is an IMA-recognized mineral species in the arsenate class, with the chemical formula As₂O₃.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Arsenolamprite-Claudetite structural group.
Key properties: Mohs hardness 2.5; specific gravity 4.14–4.15; Vitreous; pearly on cleavage surfaces luster; refractive index 1.933; optically biaxial.
IMA symbol Cdt, grandfathered status — known before the IMA’s founding, named in 1868.
A secondary oxidation product derived from realgar, arsenopyrite, or other arsenic-bearing minerals. Also produced as a sublimate during mine fires.
It is found associated with Arsenolite, realgar, orpiment, sulfur.
The mineral was named to honor Frederick Claudet, the French chemist who first described naturally occurring material.