mineral

Epidote

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

Mohs hardness of 6 to 7, distinct pistachio green to yellowish-green or black color, vitreous luster, monoclinic crystal system, perfect cleavage in one direction, specific gravity around 3.3 to 3.5.

Identified July 31, 2026More mineral →

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Physical properties

Mohs hardness of 6 to 7, distinct pistachio green to yellowish-green or black color, vitreous luster, monoclinic crystal system, perfect cleavage in one direction, specific gravity around 3.3 to 3.5.

Formation & geological history

Forms primarily through regional and contact metamorphism of igneous rocks rich in calcium and iron, such as basalt and gabbro, as well as in hydrothermal veins and skarns.

Uses & applications

Used primarily as a mineral specimen for collectors and occasionally cut into cabochons or beads for jewelry.

Geological facts

The name epidote comes from the Greek word for 'increase', referring to the base of its crystal prism being longer than the other. It is a key index mineral in greenstone facies metamorphic rocks.

Field identification & locations

Easily identified by its characteristic pistachio-green color and monoclinic prismatic habit, commonly found in metamorphic terranes worldwide, particularly in Austria, France, Norway, and the USA.