Epidote

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Pistachio green, yellowish-green, or brownish-green. Luster: Vitreous to pearly. Crystal Structure: Monoclinic with prismatic crystals. Cleavage: Perfect in one direction.

Formation & Geological History

Formed through regional or contact metamorphism of calcium-rich rocks like basalt, gabbro, or limestone. Also found in hydrothermal veins. Typical geological age varies but often associated with Alpine metamorphic events.

Uses & Applications

Used primarily as a minor gemstone, collector's specimen, and as an index mineral for geologists to identify metamorphic facies (greenschist facies).

Geological Facts

The name comes from the Greek word 'epidosis', meaning 'addition', referring to one side of the prism being longer than the others. It is one of the few minerals with a distinct 'pistachio' green color that is a primary diagnostic tool.

Field Identification & Locations

Identify by its unique 'pistachio green' color and high hardness (it can scratch glass). Found in metamorphic belts, specifically in veins or cavities within basaltic rocks.

Identified on: 4/20/2026

Mode: Standard