Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
cubicvery-rareHalides
Cryolite
Na3AlF6
This specimen displays a blocky, white to colorless, translucent mass of cryolite, exhibiting its characteristic greasy to vitreous luster. The mineral often forms pseudo-cubic crystals, though this sample appears more massive.
Cryolite Physical Properties
Mohs Hardness
2.5Crystal System
cubicLuster
vitreousStreak Color
WhiteCleavage
Poor/imperfect in three directions (pseudo-cubic)Fracture
Uneven to conchoidalSpecific Gravity
2.95Colors
colorless, white, reddish-brown, blackTransparency
Transparent to translucentType Locality
St Peters Dome, Cheyenne District (St. Peters Dome District), El Paso County, Colorado, USAMineral Group
HalidesUses
flux in aluminum production (historically), insecticide, collector's mineralAssociated Minerals
quartz, fluorite, siderite, galena, chalcopyrite, sphaleriteRarity
very-rareGeological Context
Cryolite is a rare halide mineral typically found in granite pegmatites and alkaline igneous rocks, forming during late-stage hydrothermal processes. The most significant historical deposit was Ivittuut, Greenland, where it occurred in a large pegmatite body.
