Cryolite, also known as sodium fluoroaluminate or sodium aluminum fluoride, with molecular formula of Na3AlF6, is a small white crystal, odorless, more soluble than natural cryolite, with specific gravity of 3, hardness of 2-3, melting point of 1000 ℃, easy to absorb water and moisture.

Cryolite is mainly used as a cosolvent for aluminum electrolysis, wear-resistant filler for rubber and grinding wheel, enamel opacifier, glass shading agent and metal solvent, pesticide for crops, etc.

Hall heroult method is a method of producing metal aluminum with cryolite based fluoride solution as solvent. So far, no other compound has been found to replace cryolite.