mineral

Epidote

Epidote (Ca2(Al2,Fe3+)AlSi3O12(OH))

Hardness: 6-7 Mohs; Color: Pistachio-green to dark olive green/black; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect in one direction; Specific Gravity: 3.3 to 3.5.

Hardness: 6-7 Mohs
Color: Pistachio-green to dark olive green/black
Luster: Vitreous to pearly

Identified April 3, 2026More mineral →

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Physical properties

Hardness: 6-7 Mohs; Color: Pistachio-green to dark olive green/black; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect in one direction; Specific Gravity: 3.3 to 3.5.

Formation & geological history

Formed through low to medium-grade regional metamorphism or hydrothermal alteration of igneous rocks (calcium-rich plagioclase feldspars). Commonly found in schists, gneisses, and skarns.

Uses & applications

Mainly used as a decorative collector mineral and occasionally as a minor gemstone for jewelry. It serves as an indicator mineral in geological studies of metamorphic facies.

Geological facts

The name comes from the Greek word 'epidosis' (addition), referring to the crystal sides being of unequal length. Some of the finest specimens come from the Knappenwand in Austria.

Field identification & locations

Identify in the field by its distinct 'pistachio green' color and prismatic crystal habit. Commonly found in metamorphic terrains alongside quartz, feldspar, and chlorite.