mineral

Fluorite (Rainbow Fluorite)

Calcium Fluoride (CaF2)

Hardness: 4 (Mohs scale); Color: Multi-colored banding of purple, green, and yellow; Luster: Vitreous (glassy); Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.175 - 3.184.

Hardness: 4 (Mohs scale)
Color: Multi-colored banding of purple, green, and yellow
Luster: Vitreous (glassy)

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal activity where hot, mineral-rich fluids circulate through fractures in limestone or other host rocks. Common in vein deposits and as a gangue mineral in metallic ores. Formed across various geological ages from the Precambrian to present day.

Uses & applications

Used industrially as a flux in smelting and in the production of glass and hydrofluoric acid. High-quality specimens are used in jewelry (cabs or beads), ornamental carvings, and specialized optical lenses for microscopes and telescopes.

Geological facts

Fluorite is highly fluorescent under UV light (where the term 'fluorescence' originated). It is the state mineral of Illinois and has been used by ancient Romans to carve decorative cups and vases, known as 'Blue John' carvings in England.

Field identification & locations

Identify in the field by its distinctive four-directional octahedral cleavage, hardness (it can be scratched by a steel knife but not a penny), and characteristic color banding. Found globally in locations such as China, Mexico, England (Durham), and the USA (Illinois, Kentucky).

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