Smithsonite is zinc carbonate, a secondary mineral of zinc ore deposits, usually found in botryoidal masses. It can be found in a rainbow of colors caused by partial replacement of zinc by other minerals such as copper in the case of green smithsonite and cobalt in pink smithsonite. A member of the calcite group of minerals, smithsonite has a trigonal crystal system.
Chemical composition: ZnCO3
Hardness: 4-4.5