mineral

Fluorite

Calcium fluoride (CaF2)

Hardness: 4 on Mohs scale; Color: Colorless, green, purple, blue, or yellow; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral; Specific gravity: 3.1-3.2.

Hardness: 4 on Mohs scale
Color: Colorless, green, purple, blue, or yellow
Luster: Vitreous (glassy)

Identified June 25, 2026More mineral →

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Physical properties

Formation & geological history

Typically formed in hydrothermal veins or as an accessory mineral in igneous rocks like granites. It often occurs in association with minerals like quartz, calcite, and galena.

Uses & applications

Used as a flux in steel making, in the manufacture of hydrofluoric acid, in high-performance telescopes and camera lenses (due to low dispersion), and as a popular ornamental and gemstone material.

Geological facts

Fluorite is often intensely fluorescent under UV light; the term 'fluorescence' was actually derived from this mineral. It is the index mineral for hardness level 4 on the Mohs scale.

Field identification & locations

Identified in the field by its hardness (scratched by a knife but not a copper penny) and its perfect four-directional cleavage which often results in octahedral fragments. Frequently found in China, Mexico, South Africa, and the USA (Illinois/Kentucky).