mineral

Fluorite (specifically Blue John or Banded Fluorite)

Calcium Fluoride (CaF2)

Hardness: 4 on Mohs scale; Color: Purple, white, and clear banding; Luster: Vitreous (glassy); Crystal structure: Isometric (cubic/octahedral); Cleavage: Perfect octahedral in four directions; Specific Gravity: 3.18

Hardness: 4 on Mohs scale
Color: Purple, white, and clear banding
Luster: Vitreous (glassy)

Identified June 18, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in hydrothermal veins usually through low-temperature mineral precipitates in carbonate rocks. It often occurs as a gangue mineral associated with metallic ores.

Uses & applications

Used as a flux in steel making, in the manufacture of hydrofluoric acid and opal glass, and highly valued as a gemstone or ornamental stone in the jewelry and lapidary markets.

Geological facts

Fluorite gave its name to the phenomenon of fluorescence; it glows under ultraviolet light. The 'Blue John' variety specifically found in Derbyshire, England, is world-famous for its distinct purple-blue and white banding.

Field identification & locations

Identified by its relatively low hardness (can be scratched by a knife but not a copper coin), four-directional cleavage, and cubic crystals when not tumbled. Found globally with major deposits in China, Mexico, and South Africa.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral