mineral

Fluorite Geode

Calcium Fluoride (CaF2)

Hardness: 4 on Mohs scale; Color: typically green, purple, or colorless as seen here; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral; Specific gravity: 3.18.

Hardness: 4 on Mohs scale
Color: typically green, purple, or colorless as seen here
Luster: Vitreous (glassy)

Identified July 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins and cavities when hot, mineral-rich fluids circulate through host rock. This specimen appears to be a vug or geode-like cavity filling, likely from a sedimentary or hydrothermal environment.

Uses & applications

Used as a flux in steel making, in the manufacture of hydrofluoric acid, in high-performance telescope and camera lenses, and as decorative cabinet specimens.

Geological facts

Fluorite is the most common mineral used to define the hardness of 4 on the Mohs scale. Some specimens exhibit strong fluorescence under UV light, a property named after the mineral itself.

Field identification & locations

Identify by its 4-directional cleavage and relatively low hardness (can be scratched by a knife but not a penny). Look for it in limestone or hydrothermal ore veins across locations like Illinois (USA), Mexico, and China.