mineral

Epidote

Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))

Hardness: 6-7 on Mohs scale; Color: Pistachio-green, yellow-green, or brownish-green; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect in one direction; Specific Gravity: 3.3-3.6

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

Identified February 16, 2026More mineral →

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Physical properties

Formation & geological history

Commonly formed in low-to-medium grade metamorphic rocks like greenschist. It is also found in hydrothermally altered igneous rocks and contact metamorphic zones (skarns). It often forms through the alteration of plagioclase feldspars or pyroxenes.

Uses & applications

Primarily used as a minor gemstone (cabochons) and a collector's mineral. In industry, it is a key index mineral for geologists to determine the metamorphic grade of a rock unit.

Geological facts

The name 'Epidote' comes from the Greek word 'epidosis', meaning 'addition', referring to its crystal form where one side of the prism is longer than the other. High-quality transparent crystals are rare and prized by mineral collectors.

Field identification & locations

Identify in the field by its distinct 'pistachio green' color and prismatic crystal habit. It is often found in association with quartz, chlorite, and feldspar. Common locations include the Alps, Norway, and various mountain ranges in the USA (e.g., Alaska and California).

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral