fluoriet

Fluoriet, or fluorite in English, is a mineral composed of calcium fluoride (CaF2). It is the chief source of fluorine and a common halide mineral. Fluoriet crystallizes in the cubic system and often forms cubes, octahedra, or complex interpenetrating crystals. It has a Mohs hardness of 4 and a vitreous to pearly luster. Color is highly variable, with colorless, purple, blue, green, yellow, and brown varieties, frequently displaying zoning.

A notable property of fluoriet is its fluorescence: under ultraviolet light many specimens glow, commonly blue or violet, though the color can vary with impurities such as rare earth elements. This fluorescence makes fluoriet a popular collector’s mineral and a useful diagnostic feature for identification.

Occurrence and formation: fluoriet forms in hydrothermal veins, contact metamorphic zones, and in pegmatites, often alongside quartz, calcite, sphalerite, barite, and galena. It is found in sedimentary deposits where fluorine-rich fluids have deposited CaF2. Major sources include China, Mexico, Mongolia, Spain, Russia, Argentina, and the United States, with large deposits frequently mined for industrial fluorine production.

Uses and significance: the primary industrial use of fluoriet is as a fluorine source for chemical manufacture, including the production of hydrofluoric acid and related compounds. It also serves as a flux in steelmaking and as a component in glass and ceramic formulations. In lapidary and mineral collecting, fluoriet is valued for its range of colors and fluorescence, though its relatively perfect cleavage and low hardness limit its use as a gemstone.