Cryolite is used as a solvent of the aluminum rich ore, bauxite, which is a combination of aluminum oxides such as gibbsite, boehmite and diaspore. It is very difficult to remove atoms of aluminum from atoms of oxygen which is necessary in order to produce aluminum metal. Cryolite made an excellent flux to make the process less expensive

A curious note about cryolite is the fact that it has a low index of refraction close to that of water. This means that if emersed in water, a perfectly clear colorless crystal of cryolite or powdered cryolite will essentially disappear. Even a specimen of cloudy cryolite will become more transparent and its edges will be less distinct, an effect similar to in water except that the ice floats.

• Color is clear or white to yellowish, but can also be black or purple.
• Luster is vitreous.
• Transparency crystals are transparent to translucent.
• Crystal System is monoclinic; 2/m
• Crystal Habits are usually massive and as pseudo-cubic crystals, some with psuedo-octahedral truncations.
• Cleavage is absent, but three parting directions produce what looks like a psuedo-cubic cleavage.
• Fracture is uneven.
• Hardness is 2.5 - 3
• Specific Gravity is 2.95 (average)
• Streak is white.
• Other Characteristics: index of refraction is 1.338 which is close to the index of refraction of water. As a consequence, clear cryolite crystals or powdered cryolite will nearly disappear in water. Also there is no salty taste which is helpful in distinguishing cryolite from the mineral .