Fluorit

Fluorite, often spelled fluorite in English but fluorit in some languages, is a mineral composed of calcium fluoride (CaF2) and a member of the halide mineral group. It crystallizes in the isometric (cubic) system and typically forms cubes or octahedra. The mineral has a hardness of 4 on the Mohs scale, a vitreous to pearly luster, and a specific gravity of about 3.2. It exhibits four directions of cleavage and can be transparent to translucent.

Fluorite forms in hydrothermal veins, often accompanying quartz, calcite, and metallic ores such as lead, silver, and zinc. It also occurs in granitic pegmatites and sedimentary deposits associated with fluoride-rich fluids. Colors are highly variable due to impurities; crystals may be purple, blue, green, yellow, or colorless, with zoned and banded specimens common.

Many fluorite specimens fluoresce strongly under ultraviolet light, typically glowing blue, but other colors occur. This fluorescence is a notable property and has made fluorite a collector's mineral worldwide.

Industrially, fluorite is the principal source of fluorine and a major flux material in steelmaking and in the production of hydrofluoric acid. It is also cut as a decorative stone and, in high-quality clear crystals, sold as a gemstone, though its perfect cleavage and relatively low hardness limit its use in jewelry.

The name fluorite derives from Latin fluere, to flow, in reference to its historical use as a flux in metalworking.