Xanthoconite Locality: Imiter Mine, Boumalne-Dadès, Ouarzazate Province , Souss-Massa-Draâ Region, Morocco ( Locality at mindat.org ) Picture width 1 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Xanthoconite
A yellow-orange silver-arsenic sulfosalt — the monoclinic relative of proustite.
Intro adapted from Wikipedia (CC BY-SA).
Xanthoconite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Ag₃AsS₃.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Xanthoconite structural group.
Key properties: Mohs hardness 2–3; specific gravity 5.54; Orange-yellow streak; Adamantine luster; optically biaxial.
IMA symbol Xcn, grandfathered status — known before the IMA’s founding, named in 1840.
Typically in association with other silver sulfosalts in hydrothermal veins.
It is found associated with Proustite, pyrargyrite, acanthite, arsenic, calcite.
Its name comes from the Greek for yellow and powder in allusion to its color.