mineral
Fluorite Cleavage Octahedron
Fluorite (Calcium Fluoride, CaF2)
Hardness: 4 on Mohs scale; Color: typically green, purple, or colorless; Luster: vitreous; Crystal Structure: cubic; Cleavage: perfect octahedral in four directions; Specific Gravity: 3.17 to 3.56.
- Hardness
- 4 on Mohs scale
- Color
- typically green, purple, or colorless
- Luster
- vitreous
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Physical properties
Hardness: 4 on Mohs scale; Color: typically green, purple, or colorless; Luster: vitreous; Crystal Structure: cubic; Cleavage: perfect octahedral in four directions; Specific Gravity: 3.17 to 3.56.
Formation & geological history
Formed in hydrothermal veins, often associated with metallic ores like lead and silver. It crystallizes from hot aqueous solutions as they cool or react with surrounding rocks like limestone.
Uses & applications
Used as a flux in steel making, in the manufacture of hydrofluoric acid, and for specialized optical lenses. Beautiful specimens are prized by collectors and used for decorative carvings and jewelry.
Geological facts
Fluorite is the origin of the term 'fluorescence' because many specimens glow under UV light. It is often called 'the most colorful mineral in the world'.
Field identification & locations
Identified by its octahedral shape (when cleaved), relative softness (can be scratched by a knife but not a penny), and vitreous luster. Commonly found in China, Mexico, South Africa, and the USA (Illinois/Kentucky).
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