Cryolite:
Melting point of pure alumina is 2323K which is a very high temperature and it is insulator of electricity in molten form. It’s electrolysis is very difficult. Hence in its metallurgy, fused alumina mixed with cryolite (Na3AlF6) and fluorspar (CaF2) are taken in the form of electrolyte. Their ratio is 20%, 60% and 20% respectively. Due to this, melting point of mixture reduces to about 1173K and conductivity also increases by which alumina becomes conductor.
