mineral

Fluorite on Host Rock

Calcium Fluoride (CaF2)

Hardness: 4 Hardness (Mohs scale); Color: Purple, green, clear, or yellow; Luster: Vitreous (glassy); Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.175–3.56

Hardness: 4 Hardness (Mohs scale)
Color: Purple, green, clear, or yellow
Luster: Vitreous (glassy)

Identified July 17, 2026More mineral →

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Physical properties

Hardness: 4 Hardness (Mohs scale); Color: Purple, green, clear, or yellow; Luster: Vitreous (glassy); Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.175–3.56

Formation & geological history

Forms as a late-crystallizing mineral in felsic igneous rocks through hydrothermal activity. It commonly occurs as a vein mineral in metallic ores or as a replacement in limestone/dolomite.

Uses & applications

Used in metallurgy as a flux to lower the melting point of raw materials, in the production of hydrofluoric acid, in high-performance optical lenses, and as a popular collector's mineral.

Geological facts

Fluorite was the first mineral to have its phenomenon of 'fluorescence' named after it. It is often found in breathtaking cubic or octahedral crystals that can vary significantly in color within a single specimen.

Field identification & locations

Identify by its hardness (can be scratched by a steel nail but not a copper penny) and its characteristic four directions of cleavage. Common in Derbyshire, England (Blue John), China, Mexico, and Illinois, USA.