Fluorite

Physical Properties

Hardness: 4 on Mohs scale; Color: Green (in this specimen), can also be purple, blue, yellow, or clear; Luster: Vitreous; Crystal Structure: Isometric/Cubic; Cleavage: Perfect octahedral; Specific Gravity: 3.18

Formation & Geological History

Formed in hydrothermal veins, often associated with metallic ores like lead and silver. It can also occur in vugs of limestones and dolomites. It has been forming across various geological ages from the Precambrian to more recent times.

Uses & Applications

Used as a flux in steel making, in the manufacture of hydrofluoric acid, in high-performance telescopes and camera lenses (due to low dispersion), and as a popular semi-precious gemstone for jewelry and carvings.

Geological Facts

Fluorite is the origin of the word 'fluorescence' because many specimens glow under ultraviolet light. It is often called 'the most colorful mineral in the world' due to the wide range of impurities that cause various tints.

Field Identification & Locations

Identify by its 'softer than glass' hardness (Mohs 4), its cubic crystal habit, and its distinctive octahedral cleavage. Often found in Illinois (USA), China, Mexico, and South Africa.

Identified on: 4/18/2026

Mode: Standard