I found this piece in a flat of idle dealer stock from the 1980’s. It is labeled as dioptase on conichalcite. It is entirely possible, but it could also be duftite or mottramite or any number of secondary copper minerals. It is a very attractive piece with bright emerald green dioptase covering most of the display side. Locality: Tsumeb Mine, Tsumeb, Namibia Composition: hydrated copper silicate on calcium copper arsenate hydroxide
