mineral

Epidote

Epidote - {Ca2}{Al2Fe3+}(Si2O7)(SiO4)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 - 3.5.

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

Identified March 21, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily through regional or contact metamorphism of calcium-rich rocks like basalt, gabbro, or limestone; often found in hydrothermal veins and altered igneous rocks (epidotization).

Uses & applications

Used primarily as a minor gemstone or for lapidary work (cabochons). High-quality crystals are prized by collectors. It is also an indicator mineral for geologists identifying metamorphic facies.

Geological facts

The name comes from the Greek word 'epidosis' meaning 'addition,' referring to one side of the prism being longer than the other. It is the signature mineral of the 'Greenschist' metamorphic facies.

Field identification & locations

Identify in the field by its distinct 'pistachio' green color and its association with quartz or feldspar. Commonly found in Alpine veins, the Ural Mountains, and parts of the United States like Alaska and California.