Aluminium is produced by electrolytic reduction of aluminium oxide dissolved in molten cryolite. The electrowinning of aluminium relies on the electrolysis of aluminium fluoride in molten cryolite. Foremost are NaAlF, cryolite, and AlF, aluminium trifluoride. The electrolyte is made up of molten cryolite and other additives. This accounts for the exsolved kesterite in stannite found in the cryolite. Aluminium nitride is resistant to attack from most molten salts, including chlorides and cryolite. The electrolyte is a molten bath of cryolite (NaAlF) and dissolved alumina. This aluminium oxide is dissolved at a temperature of about in molten cryolite. Other solid deposits include halite, amphibole, cryolite, nitratine, and zeolite. Fluorite, fluorapatite and cryolite are the most industrially significant. A few ocular prostheses today are made of cryolite glass. The resultant HF is mostly used to produce organofluorides and synthetic cryolite. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Pikes Peak's rock formations contained the mineral cryolite, one of whose constituents is fluorine. Cryolite (), used in the production aluminium, is the most fluorine-rich mineral.