mineral

Epidote

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

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

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

Identified March 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed via regional or contact metamorphism of calcium-rich rocks like basalt, gabbro, or limestone. It typically occurs in low-to-medium grade metamorphic facies (greenschist facies) and hydrothermal veins. Geological age varies by locality, ranging from Precambrian to Cenozoic.

Uses & applications

Primarily used as a minor gemstone (cabochon or faceted) for collectors and in decorative carvings. It is also an important index mineral for geologists to identify metamorphic temperature and pressure conditions.

Geological facts

The name 'epidote' comes from the Greek word 'epidosis', meaning 'addition', referring to the crystal's geometry. Pistacite is a common synonym due to its signature pistachio color.

Field identification & locations

Identify in the field by its distinct 'pistachio green' color and striated columnar crystals. Commonly found in alpine veins (French Alps), Norway, and across North America (specifically the Blue Ridge Mountains). Collectors look for well-terminated, dark green glassy crystals.