mineral

Fluorite

Calcium Fluoride (CaF2)

Hardness: 4 on Mohs scale; Color: typically purple, green, or blue in rough samples; Luster: Vitreous (glass-like); Crystal structure: Isometric (cubic); Cleavage: Perfect octahedral in four directions; Specific gravity: 3.175 to 3.184.

Hardness: 4 on Mohs scale
Color: typically purple, green, or blue in rough samples
Luster: Vitreous (glass-like)

Identified March 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a hydrothermal mineral in veins, often associated with metallic ores like lead and silver, or in hot spring deposits. It can occur in sedimentary rocks as well. It spans many geological ages, common in deposits from the Carboniferous Period to modern formations.

Uses & applications

Used in industry as a flux for smelting steel and aluminum (fluorspar). In aesthetics, it is used for ornamental carving, jewelry (though fragile), and as a popular specimen for mineral collectors. High-quality clear fluorite is used for specialized optical lenses.

Geological facts

Fluorite is the most colorful mineral in the world, earning the nickname 'the most colorful mineral.' It is where the word 'fluorescence' comes from, as many specimens glow under ultraviolet light. Pure fluorite is actually colorless; the vibrant colors come from impurities or radiation damage.

Field identification & locations

Identify in the field by its cubic crystal habit, its 4-point cleavage, and its relative softness (it can be scratched by a steel knife but not a copper penny). It is commonly found in Illinois (state mineral), China, Mexico, and South Africa. Collectors look for sharp, undamaged cubic crystals.