Domeykite. No locality given. Mineral collection of Bringham Young University Department of Geology, Provo, Utah. Photograph by Andrew Silver. BYU index 2-9008, Cu_3As. — Photo: Wikimedia Commons · Public domain
Domeykite
Copper arsenide — a white-to-gray metallic mineral that weathers brassy, usually massive or botryoidal rather than crystalline.
Intro adapted from Wikipedia (CC BY-SA).
Domeykite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Cu₃As.
It crystallizes in the cubic crystal system (space group I-43d). It is a member of the Domeykite structural group.
Key properties: Mohs hardness 3–3.5; specific gravity 7.2–7.9; Metallic. R: (400) 41.1, (420) 41.4, (440) 41.7, (460) 43.1, (480) 45.2, (500) 47.5, (520) 49.3, (540) 50.7 luster.
IMA symbol Do, grandfathered status — known before the IMA’s founding, named in 1845.
Hydrothermal in origin.
It is found associated with Copper (typically arsenian), silver, algodonite.
The mineral was named to honor Professor Ignacio Domeyko [born Ignacy Domejko] (1802–1889), Polish–Chilean mineralogist, University of Chile, Santiago, Chile.