Cryolite

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Cryolite, mineral, sodium aluminum fluoride (Na3AlF6). Cryolite has a hardness of 2.5 and a specific gravity of about 3. It crystallizes in the monoclinic system (see Crystal). It is colorless and ranges from transparent to translucent. It has a waxy appearance, making it almost invisible when powdered and suspended in water. Cryolite was found in abundance only at Ivigut, Greenland. However, that deposit has been exhausted since 1987. The mineral is still found in small quantities in Colorado, USA; Sallent, Huesca Province, Spain; Miask, Urals, USSR; and Montreal, Quebec, Canada. It is used chiefly as a solvent of alumina in the electrolytic preparation of aluminum. Because of its scarcity, this mineral has been replaced in industrial processes by artificially produced sodium aluminum fluoride.

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