Cryolite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameCryolite
Chemical FormulaNa3AlF6
Mohs Hardness2.5
Crystal Systemmonoclinic
Streak Colorwhite
Cleavageimperfect in three directions (pseudo-cubic)
Fractureuneven to subconchoidal
Specific Gravity2.95
Colorswhite, colorless, yellowish-brown
Transparencytranslucent
Type LocalityIvigtut Cryolite deposit, Ivittuut (Ivigtut), Arsuk Firth, Arsuk, Kitaa (West Greenland) Province, Greenland
Mineral Grouphalides
Usesaluminum production (historical), enamel, glass, insecticide, collector
Associated Mineralsquartz, siderite, galena, sphalerite, fluorite
Rarityrare
Description
This specimen is a massive, off-white to yellowish-white chunk of cryolite, exhibiting a somewhat greasy or waxy luster. Its translucent nature allows some light to pass through, highlighting its characteristic appearance.
Geological Context
Cryolite typically forms in pegmatites and hydrothermal veins, often associated with alkaline igneous rocks. The Ivigtut deposit, now exhausted, was a unique, large cryolite-rich pegmatite formed in a granitic intrusion.
