mineral
Fluorite (specifically Blue John or Banded Fluorite)
Calcium Fluoride (CaF2)
AI-generated identification · may be incorrectHardness: 4 on Mohs scale; Color: Purple, white, and clear banding; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral in four directions; Specific Gravity: 3.18
- Hardness
- 4 on Mohs scale
- Color
- Purple, white, and clear banding
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 4 on Mohs scale; Color: Purple, white, and clear banding; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral in four directions; Specific Gravity: 3.18
Formation & geological history
Formed in hydrothermal veins usually through low-temperature mineral precipitates in carbonate rocks. It often occurs as a gangue mineral associated with metallic ores.
Uses & applications
Used as a flux in steel making, in the manufacture of hydrofluoric acid and opal glass, and highly valued as a gemstone or ornamental stone in the jewelry and lapidary markets.
Geological facts
Fluorite gave its name to the phenomenon of fluorescence; it glows under ultraviolet light. The 'Blue John' variety specifically found in Derbyshire, England, is world-famous for its distinct purple-blue and white banding.
Field identification & locations
Identified by its relatively low hardness (can be scratched by a knife but not a copper coin), four-directional cleavage, and cubic crystals when not tumbled. Found globally with major deposits in China, Mexico, and South Africa.
