mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

Hardness: 6-7 on Mohs scale. Color: Pistachio-green to brownish-black. Luster: Vitreous to pearly. Crystal structure: Monoclinic, often prismatic or acicular. Cleavage: Perfect in one direction. Specific gravity: 3.3-3.6.

Hardness: 6-7 on Mohs scale
Color: Pistachio-green to brownish-black
Luster: Vitreous to pearly

Identified March 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed in low- to medium-grade metamorphic rocks (schists and gneisses) or through hydrothermal alteration of igneous rocks like basalt and gabbro. Most specimens are from the Phanerozoic eon, typically found in contact metamorphic zones.

Uses & applications

Predominantly used as a semi-precious gemstone (when high quality) and as a collector's mineral specimen. It has minor industrial use as an indicator mineral in mineral exploration.

Geological facts

The name comes from the Greek 'epidosis' meaning 'increase', referring to the crystal base being longer on one side. It is the defining mineral for the 'Epidote Facies' in metamorphic petrology.

Field identification & locations

Identify in the field by its characteristic 'pistachio-green' color and prismatic crystals with longitudinal striations. Common locations include Knappenwand (Austria), Alaska, and Pakistan. Collectors should look for luster and well-defined crystal terminations.