Fluorite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameFluorite
Chemical FormulaCaF₂
Mohs Hardness4
Crystal Systemcubic
Lustervitreous
Streak Colorwhite
Cleavageperfect octahedral on {111}
Fractureuneven to conchoidal
Specific Gravity3.18
Colorspurple, violet, colorless, blue, green, yellow, pink, red, brown, black
Transparencytransparent to translucent
Type LocalityBoltsburn Mine, Rookhope District, Weardale, North Pennines, Co. Durham, England, UK
Mineral GroupHalides
Usesflux in steelmaking, source of hydrofluoric acid, optical lenses, jewelry, collector specimens
Associated Mineralsquartz, calcite, barite, galena, sphalerite
Raritycommon
Description
The image displays a cluster of intergrown purple fluorite crystals, exhibiting their characteristic cubic habit, on a dark matrix. Under ultraviolet light, the fluorite fluoresces a vibrant blue.
Geological Context
Fluorite commonly forms in hydrothermal veins, often associated with metallic ores, and can also be found in granites, pegmatites, and some sedimentary rocks. Its formation is typically from fluorine-rich fluids at moderate temperatures.
