Formula: As2O3
Simple oxide, claudetite group, paramorph of arsenolite
Specific gravity:
Hardness: 2½
Streak: White
Colour: Colourless, white
Solubility: Soluble in hot alkali solutions (Dana )

Hydrothermal environments

Claudetite occurs as a secondary oxidation product derived from realgar, orpiment, arsenopyrite, or other arsenic-bearing minerals, or as a sublimation product of mine fires (Webmin, HOM). Associated minerals include arsenolite, realgar, orpiment and sulphur (HOM).


At the La Salle mine, France, claudetite has been found with native sulphur and orpiment (Dana ).

The type locality is the São Domingos mine, Corte do Pinto, Mértola, Beja, Portugal.

At Imperial county, California, USA, about 50 km north of Yuma, Arizona, claudetite has been found as an alteration product of realgar (Dana ).

At Island Mountain, Coastal Range, Trinity county, California, USA, claudetite has been found as crusts in the gossan of a pyrrhotite deposit (Dana ).

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