Fluorite Octahedron

Physical Properties

Hardness: 4 on Mohs scale; Color: Green (in this specimen), can range through purple, blue, yellow, and clear; Luster: Vitreous (glassy); Crystal Structure: Cubic, but cleaves into octahedrons; Cleavage: Perfect octahedral in four directions; Specific Gravity: 3.18

Formation & Geological History

Forms primarily in hydrothermal veins, often associated with metallic ores like lead and silver. It can also be found in vugs within sedimentary rocks like limestone. It is found in deposits dating from various geological eras.

Uses & Applications

Used as a flux in steel making, as a source for fluorine in chemical manufacturing (hydrofluoric acid), for high-quality camera and telescope lenses, and as popular decorative specimens for collectors.

Geological Facts

Fluorite is the origin of the term 'fluorescence' because many specimens glow under ultraviolet light. It is often called 'the most colorful mineral in the world' due to the wide variety of vibrant hues it can exhibit.

Field Identification & Locations

Identify in the field by its distinct 4-directional cleavage (creating the double-pyramid shape), its relatively low hardness (can be scratched by a steel knife), and its glassy luster. Common locations include Illinois and Kentucky (USA), China, and England.

Identified on: 5/2/2026

Mode: Standard