Definition and Uses :
Historically used as an aluminum ore and later in the electrolytic processing of the aluminum-rich oxide ore bauxite (itself a combination of aluminum oxide minerals such as gibbsite, boehmite, and diaspore). The difficulty of separating aluminum from oxygen in oxide ores has been overcome by using cryolite as a flux to dissolve the oxide minerals. Pure cryolite itself melts at 1012 °C (1285 K) and can melt aluminum oxides well enough to allow easy removal of aluminum by electrolysis. Considerable energy is still required to heat the materials and electrolysis, but it would be much more energy efficient than melting the oxides. Since natural cryolite is too scarce to be used for this purpose, synthetic sodium aluminum fluoride is produced from the common mineral fluorite.