Cryolite (Na3AlF6, sodium hexafluoroaluminate) is an uncommon mineral.Cryolite occurs as glassy, colorless, white-reddish to gray-black prismaticmonoclinic crystals. It has a Mohs hardness of 2.5 to 3 and a specific gravity of about 2.95 to 3.0. It is translucent to transparent with a verylow refractive index of about 1.34, which is very close to that of water;thus if immersed in water, cryolite becomes essentially invisible.
Features:
When used in electrolytic aluminum industry, the consumption of sodium fluoride or soda can be saved and the production cost of electrolytic aluminum can be reduced.