mineral

Rainbow Fluorite

Fluorite (Calcium Fluoride, CaF2)

Hardness: 4 (Mohs scale), Color: Banded purple, yellow, and clear; Luster: Vitreous (glassy); Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.18

Hardness: 4 (Mohs scale), Color: Banded purple, yellow, and clear
Color: Banded purple, yellow, and clear
Luster: Vitreous (glassy)

Identified March 18, 2026More mineral →

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Physical properties

Hardness: 4 (Mohs scale), Color: Banded purple, yellow, and clear; Luster: Vitreous (glassy); Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.18

Formation & geological history

Formed through hydrothermal activity where hot, mineral-rich fluids circulate through fractures in limestone or igneous rocks. Most commercial specimens are from the Phanerozoic eon, found in vein deposits or as replacement minerals.

Uses & applications

Used as a flux in steel and aluminum smelting, in the production of hydrofluoric acid, high-precision optical lenses, and extensively in the jewelry and lapidary arts for decorative points and beads.

Geological facts

Fluorite is the most colorful mineral in the world. It is the eponymous mineral for 'fluorescence' because many specimens glow blue or violet under ultraviolet light due to trace impurities.

Field identification & locations

Identify in the field by its distinct cubic habit, perfect cleavage, and the fact that it can be scratched by a steel knife but not a copper penny. Common locations include China, Mexico, South Africa, and Illinois, USA (where it is the state mineral).