Cassiterite Ore Stone Isolated On White Background. Rock Forming Minerals. Tin Mineral Stone. Royalty-Free Stock Image

Cassiterite, also called tinstone, heavy, metallic, hard tin dioxide that is the major ore of tin. It is colourless when pure, but brown or black when iron impurities are present. Commercially important quantities occur in placer deposits, but cassiterite also occurs in granite and pegmatites.