Cryolite or kryolite mineral usually pure white or colorless but sometimes tinted in shades of pink, brown, or even black and having a luster like that of wax.
Chemically, it is a double fluoride of sodium and aluminum, Na3AlF6. Its principal use is as a flux in the smelting of aluminum. It is used also as a source of soda, aluminum salts, fluorides, and hydrofluoric acid (by the action of sulfuric acid).