mineral

Epidote

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

Hardness: 6-7 Mohs; Color: Pistachio-green, yellow-green, or brownish-green; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect longitudinal; Specific Gravity: 3.3-3.6

Hardness: 6-7 Mohs
Color: Pistachio-green, yellow-green, or brownish-green
Luster: Vitreous to pearly

Identified June 27, 2026More mineral →

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Physical properties

Hardness: 6-7 Mohs; Color: Pistachio-green, yellow-green, or brownish-green; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect longitudinal; Specific Gravity: 3.3-3.6

Formation & geological history

Formed in metamorphic rocks (schist, gneiss) through regional metamorphism or hydrothermal alteration of igneous rocks like basalt and gabbro. Often found in contact metamorphic zones.

Uses & applications

Primarily used as a minor gemstone, for ornamental carvings, and as a popular specimen for mineral collectors. Some varieties like Unakite (epidote with orthoclase) are used in jewelry.

Geological facts

Epidote gets its name from the Greek word 'epidosis' meaning 'addition' or 'increase', referring to the unequal sides of the crystal base. It is a key indicator mineral for the greenschist metamorphic facies.

Field identification & locations

Identify in the field by its characteristic 'pistachio-green' color and association with other metamorphic minerals like quartz, chlorite, and feldspar. Commonly found in alpine vein deposits and metamorphic terrains worldwide.