Sodium Cryollite

Cryolite 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.

The History Says Mining for cryolite was started in 1854 and continued until 1987 at Ivittuut. The most important mine in recent times was the Maarmorilik mine, which produced zinc, lead and silver during the period from 1973 to 1990. In total more than 20 different mining operations are known from the last 150 years.

The Present Scenario The commercial application of cryolite is confined mainly to aluminium metallurgy, where it is used as an electrolyte in the reduction of alumina to aluminium metal by the Hall process.

The mineral cryolite is a double fluoride of sodium and aluminium (3NaF, ALF3). It crystallizes in momoclinic system. It is snow-white in colour and can be distinguished easily from any identical mineral by its colour. Theoretically, it contains 54.4% fluorine, 12.8% aluminium and 32.8% sodium. Its sp. gr. Is 2.96 and hardness 2.5. the refractive index is about 1.339 so close to water that this mineral becomes invisible when immersed in water. Its snow-white colour gives one distinct advantage in identifying it megascopically.