Sphalerite ((Zn,Fe)S)'s a mineral that's the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content's high it's an opaque black variety, marmatite. It's usually found in association with galena, pyrite, and other sulfides along with calcite, dolomite, and fluorite. Miners have also been known to refer to sphalerite as zinc blende, mock lead, false galena and black-jack. The mineral crystallizes in the cubic crystal… (More on Zincblende)