The zinc carbonate Smithsonite was abundant throughout the Tsumeb mine in Namibia, occurring in the supergene and all three oxidation zones. As mine development progressed to ever deeper levels, Smithsonite was often found containing copper (cuprian); cobalt (cobaltoan); manganese (manganoan) and cadmium. This ex-matrix cluster of three interpenetrant rhombohedral crystals is the variety Cadmium Smithsonite, made quite apparent by its distinct mustard-yellow to lemon colour. The central crystal is the largest, measuring 2 cm on its longest edge and, as is a characteristic of Smithsonite, all edges of the rhombohedron are slightly outwardly convex-curved. The crystals have translucent outer shells which catch and reflect incident light, causing the surface layers to glow, while the inner cores are opaque. Th base is coloured silver-grey with inclusions of, most likely, Galena within tiny Smithsonite crystals. A lovely Cadmium Smithsonite from Tsumeb.
