Cryolite

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Description

White, translucent crystalline mineral composed of sodium aluminum fluoride. Cryolite occurs naturally in Greenland (Ivigtut) with smaller sources located Spain, U.S.(Colorado) and Russia. It may also be made synthetically by fusing sodium fluoride and aluminum fluoride. Cryolite is used as a flux and opacifier in porcelain enamel. It is also used to make opalescent glass.

Synonyms and Related Terms

sodium aluminum fluoride; Greenland spar; icestone; ice stone; criolita (Esp.); cryolite (Fr.); Kryolit (Deut.)

Other Properties

Soluble in concentrated sulfuric acid. Taste is slightly salty.

Monoclinic, prismatic crystals usually occuring in masses or granules.

Fracture = uneven. Luster = vitreous to greasy. Streak = white.

Composition Na3AlF6
Mohs Hardness 2.5
Melting Point 1000
Density 2.95-3.0
Refractive Index 1.338;1.338;1.339

Hazards and Safety

Toxic by ingestion and inhalation. May cause dental and bone defects. Gives off poisonous fluorine gas during firing.

Additional Information

Mineralogy Database: Cryolite

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