mineral

Fluorite

Calcium fluoride (CaF2)

Hardness: 4 (Mohs scale), Color: Pale green (common), Luster: Vitreous/glassy, Crystal structure: Cubic/Isometric, Cleavage: Perfect octahedral, Specific Gravity: 3.175-3.56

Identified July 7, 2026More mineral →

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Physical properties

Hardness: 4 (Mohs scale), Color: Pale green (common), Luster: Vitreous/glassy, Crystal structure: Cubic/Isometric, Cleavage: Perfect octahedral, Specific Gravity: 3.175-3.56

Formation & geological history

Formed primarily through hydrothermal activity in ore veins or as a late-stage crystallization in igneous rocks like granite. Often found in limestone and dolomite through limestone-replacement processes.

Uses & applications

Used as a flux in steel making, in the manufacture of hydrofluoric acid, in high-performance telescopes and cameras lenses, and as a popular semi-precious ornamental stone for jewelry and carving.

Geological facts

Fluorite is often called the 'most colorful mineral in the world.' It gave rise to the term 'fluorescence' because many specimens glow under ultraviolet light. It is the state mineral of Illinois.

Field identification & locations

Identified in the field by its relatively low hardness (can be scratched by a knife), its characteristic cubic crystal shape, and its perfect four-way cleavage. Common in mining districts worldwide, notably in China, Mexico, and the USA.