Fluorite

Physical Properties

Hardness: 4 on Mohs scale; Color: typically green, purple, blue, or colorless (this specimen is a pale green/clear); Luster: Vitreous; Crystal Structure: Isometric; Cleavage: Perfect octahedral.

Formation & Geological History

Formed in hydrothermal veins often alongside metallic ores like lead and silver, or in hot spring deposits and carbonate rocks. It can form at various temperatures and is found in geological formations spanning from the Precambrian to the present.

Uses & Applications

Used as a flux in steel making, in the manufacture of opal glass and enamels, for high-performance camera lenses (using synthetic crystals), and as a popular ornamental and collector mineral.

Geological Facts

Fluorite is where the term 'fluorescence' came from because many specimens glow under ultraviolet light. It is often called 'the most colorful mineral in the world'.

Field Identification & Locations

Identify in the field by its hardness (softer than quartz/glass, harder than calcite), its octahedral cleavage (it often breaks into pyramid-like shapes), and its response to UV light. Found widely in China, Mexico, South Africa, and the USA (notably Illinois).

Identified on: 4/17/2026

Mode: Standard