Cryolite (Na3AlF6, sodium hexafluoroaluminate) is an uncommon mineral identified with the once-large deposit at Ivittuut on the west coast of Greenland, depleted by 1987.
Formula mass：209.9 g mol−1
Color：Colorless to white, also brownish, reddish and rarely black
Crystal habit：Usually massive, coarsely granular. The rare crystals are equant and pseudocubic
Mohs scale hardness：2.5 to 3
Melting point：1012 °C
Solubility：Soluble in AlCl3 solution, soluble in H2SO4 with the evolution of HF, which is poisonous. Insoluble in water.
Cryolite is used as an insecticide and a pesticide. It is also used to give fireworks a yellow color. Molten cryolite is used as a solvent for aluminium oxide (Al2O3) in the Hall–Héroult process, used in the refining of aluminium. It decreases the melting point of molten (liquid state) aluminium oxide from 2000–2500 °C to 900–1000 °C, and increases its conductivity thus making the extraction of aluminium more economical.