mineral
Epidote
Epidote {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
AI-generated identification · may be incorrectHardness: 6-7 (Mohs scale), Color: Pistachio-green to yellow-green or brownish-black, Luster: Vitreous to resinous, Crystal Structure: Monoclinic, Cleavage: Perfect in one direction, Specific Gravity: 3.3-3.6
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Pistachio-green to yellow-green or brownish-black, Luster: Vitreous to resinous, Crystal Structure: Monoclinic, Cleavage: Perfect in one direction, Specific Gravity: 3.3-3.6
Formation & geological history
Formed during low-to-medium grade regional metamorphism of calcium-rich rocks like basalt, gabbro, or limestone. It often occurs in hydrothermal veins and vugs in igneous and metamorphic rocks.
Uses & applications
Primarily of interest to collectors and geologists; occasionally used as a minor gemstone (cabochons) when found in large, transparent crystals, or as a decorative stone (Unakite).
Geological facts
The name comes from the Greek word 'epidosis' meaning 'addition', referring to the crystal's base being longer on one side. It is a key index mineral for the greenschist metamorphic facies.
Field identification & locations
Identify in the field by its characteristic 'pistachio' green color and prismatic crystal habit. Commonly found in alpine veins, contact metamorphic zones, and altered volcanic rocks. Found globally in locations like Austria, Norway, and the USA.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous
Septarian Pebble
Septarian nodule / Concretion
sedimentary