Sphalerite is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is 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, black-jack, and ruby jack.
Sphalerite, over 100 Carats, Santander, Spain Sphalerite, a zinc iron sulfide, is usually found in black and very rarely in the rich orange color seen here—and it is rarely seen cut into a gemstone. The luster of sphalerite is its strongest attribute, i.e. it is adamantine, with a high refractive index and brilliance greater than diamonds.
Zinc sulfide - Mixtures of zinc and sulfur react pyrotechnically, leaving behind zinc sulfide - Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various impurities, the pure material is white, and it is widely used as a pigment.