mineral

Fluorite

Calcium Fluoride (CaF2)

Hardness: 4 on the Mohs scale; Color: Variable (blue, green, purple, yellow, or clear); Luster: Vitreous (glassy); Crystal Structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral in four directions; Specific Gravity: 3.175 to 3.56.

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

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Primary formation occurs in hydrothermal veins, often as a gangue mineral associated with metallic ores (lead, silver, zinc). It can also be found in vugs in sedimentary rocks like limestone. It is found in deposits ranging from Proterozoic to Cenozoic ages.

Uses & applications

Industry: Flux for steel and aluminum smelting, manufacturing of hydrofluoric acid. Jewelry: Used as a semi-precious gemstone (though soft). Science: High-quality lenses for microscopes and telescopes due to low dispersion.

Geological facts

Fluorite is the most colorful mineral in the world. The term 'fluorescence' was coined because many fluorite specimens glow under ultraviolet light. A famous variety from England is known as 'Blue John,' which was used for ornamental bowls and vases.

Field identification & locations

Identification: Look for a glassy luster and characteristic 4-way octahedral cleavage visible in cracks. It is easily scratched by a steel knife but can scratch a copper coin. Common locations include China, Mexico, South Africa, and the USA (Illinois/Kentucky). Collectors should look for distinct color zoning and clarity.