domeykite

domeykite, a copper arsenide mineral (formulated Cu₃As) that is often intergrown with algodonite, another copper arsenide. Both are classified among the sulfide minerals, although they contain no sulfur. They occur in Chile, in Keweenaw County, Mich., and in other localities. Domeykite crystallizes in the isometric system. For detailed physical properties, see sulfide mineral (table).