Fluorite

Physical Properties

Hardness: 4 on Mohs scale; Color: Green, purple, blue; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic); Cleavage: Perfect octahedral; Specific gravity: 3.175–3.184.

Formation & Geological History

Formed in hydrothermal veins, often alongside metallic minerals like lead and silver. It crystallizes from fluids moving through the Earth's crust in a variety of geological settings from sedimentary to igneous environments.

Uses & Applications

Used as a flux in steel making, in the manufacture of opalescent glass, lenses for microscopes/telescopes, and as a popular semi-precious gemstone for jewelry and carvings.

Geological Facts

Fluorite gave its name to the phenomenon of fluorescence because many specimens glow under ultraviolet light. It is often referred to as 'the most colorful mineral in the world'.

Field Identification & Locations

Identified by its relatively low hardness (can be scratched by a knife but not a copper coin), its cubic crystal habit, and its characteristic green/purple color banding. Commonly found in China, Mexico, South Africa, and the USA (Illinois/Kentucky).

Identified on: 5/16/2026

Mode: Standard