mineral

Epidote

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

Hardness: 6-7 Mohs; Color: Pistachio-green, yellowish-green, or brownish-green; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in one direction; Specific gravity: 3.3 to 3.6

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

Identified June 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed through regional metamorphism of calcium-rich rocks or hydrothermal alteration of igneous rocks like basalt. It often occurs in veins, vugs, or as a secondary mineral in altered volcanic rocks.

Uses & applications

Primarily of interest to mineral collectors. Occasionally used as a minor gemstone (unakite) or as a decorative stone when found in larger masses. In industry, it can serve as an indicator of hydrothermal ore deposits.

Geological facts

The name comes from the Greek word 'epidosis', meaning 'addition', referring to the crystal's geometry. It is often found associated with quartz, calcite, and actinolite.

Field identification & locations

Identify in the field by its distinctive 'pistachio' green color and its environment in metamorphic or altered igneous terrain. It is common in areas like the Alps, Norway, and various basaltic formations in the US.