mineral

Fluorite (Polished Egg)

Calcium Fluoride (CaF2)

AI-generated identification · may be incorrect

Hardness 4 on the Mohs scale, vitreous (glassy) luster, isometric crystal system with perfect octahedral cleavage in four directions, specific gravity around 3.18. Displays color zoning with rich purple, violet, clear, and dark tones.

Identified October 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in hydrothermal veins associated with metallic ores, as well as in cavities of sedimentary rocks like limestone and dolostone. Often deposited by fluorine-bearing fluids circulating through crustal fractures.

Uses & applications

Extensively used in ornamental carvings, lapidary spheres and eggs, and jewelry. Industrially, fluorite (fluorspar) is critical as a flux in steelmaking, in hydrofluoric acid production, and in optical lenses.

Geological facts

Fluorite gave its name to the phenomenon of 'fluorescence' because many specimens glow vividly blue or violet under ultraviolet light due to trace rare earth elements. It is also naturally brittle and soft, requiring careful polishing.

Field identification & locations

Identified by its defining Mohs hardness of 4 (can be scratched by a knife or copper coin, but will scratch calcite) and its distinctive four-directional octahedral cleavage cracks visible internally. Notable localities include China, Mexico, England (Blue John), and Illinois, USA.