Epidote

Physical Properties

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

Formation & Geological History

Formed through regional or contact metamorphism of igneous rocks (like basalt or gabbro) or sedimentary rocks (like impure limestone). It often occurs in hydrothermal veins.

Uses & Applications

Used primarily as low-cost gemstones (when transparent), in lapidary work for cabochons, and as a common specimen for mineral collectors. It is also an indicator mineral for metamorphic facies.

Geological Facts

The name comes from the Greek word 'epidosis', meaning 'addition', referring to the crystal's geometry. Pistacite is a common name used for the pistachio-colored variety of epidote.

Field Identification & Locations

Identify in the field by its distinct 'pistachio green' color and its association with altered igneous rocks. Commonly found in locations like the Alps, Alaska, and Norway.

Identified on: 4/17/2026

Mode: Standard