# How to identify epidote

Canonical page: https://lithomap.app/resources/mineral-identification/epidote
Last reviewed: September 17, 2026
Page purpose: Original LithoMap mineral identification reference for field observations, search systems, and language models.
Classification: Calcium aluminum iron sorosilicate · Ca₂(Al,Fe)₃(SiO₄)₃(OH)

## Summary

Epidote is commonly a pistachio-green to yellow-green mineral with prismatic habit, glassy luster, one perfect cleavage, and hardness near 6 to 7, widespread in metamorphic and altered rocks.

## Quick identification clues

- Pistachio, yellow-green, or dark green color
- Mohs hardness about 6 to 7
- Prismatic, granular, or radiating habit
- One perfect cleavage direction

## Composition and classification

Epidote contains calcium, aluminum, iron, silicon, oxygen, and hydroxyl. Iron content strongly influences color and optical properties, and epidote belongs to a broader mineral group with related species.

## Appearance

Crystals are commonly elongate, striated, or bladed with yellow-green to dark green color and vitreous luster. It also occurs as granular aggregates, vein fillings, coatings, or fine disseminations.

Massive epidote can give altered rock a distinctive pistachio-green cast. Dark specimens may resemble hornblende, tourmaline, or pyroxene without close inspection.

## Identification tests

- Hardness: About 6 to 7. Commonly scratches glass and is much harder than chlorite or serpentine.
- Cleavage: One perfect direction. May produce flat reflective breaks along elongate crystals.
- Streak: White to gray. Separates it from green-streaking malachite.
- Color: Characteristic pistachio to yellow-green in many samples. Helpful but not sufficient alone.

## Common lookalikes

- Olivine: Usually granular with poor cleavage and occurs prominently in mafic or ultramafic igneous rocks.
- Malachite: Much softer, leaves a green streak, and commonly forms banded or botryoidal carbonate material.
- Tourmaline: Commonly triangular in cross section with strong lengthwise striations and poor cleavage.

## Direct side-by-side comparisons

- Epidote vs. olivine — https://lithomap.app/resources/mineral-identification/compare/epidote-vs-olivine

## Most relevant related guides

- Olivine — https://lithomap.app/resources/mineral-identification/olivine
- Malachite — https://lithomap.app/resources/mineral-identification/malachite
- Tourmaline — https://lithomap.app/resources/mineral-identification/tourmaline
- Apatite — https://lithomap.app/resources/mineral-identification/apatite

## Formation

Epidote forms during low- to moderate-grade metamorphism, hydrothermal alteration, and chemical replacement of plagioclase and other calcium-bearing minerals.

It is common in greenschist-facies rocks, skarns, veins, altered volcanic rocks, and around igneous contacts, often with chlorite, actinolite, albite, quartz, or calcite.

## Occurrence and geologic setting

Epidote is widespread in metamorphic belts and hydrothermally altered igneous rocks. It can occur as attractive crystals in veins or as abundant fine green alteration.

A green altered rock may contain epidote with chlorite and actinolite; the whole rock should not automatically be named for one color.

## Uses and significance

Transparent epidote is occasionally faceted for collectors, and attractive crystals are collected. Its chief geological importance is as an indicator of metamorphism and hydrothermal alteration.

## Field safety and limitations

- Confirm hardness before relying on green color.
- Do not scratch transparent or well-formed crystals.
- Altered slopes and mine workings may be fractured and unstable.

## Authoritative sources

- Minerals and their physical properties — U.S. National Park Service: https://www.nps.gov/subjects/geology/minerals.htm
- Mohs Hardness Scale — U.S. National Park Service: https://www.nps.gov/articles/mohs-hardness-scale.htm
- Natural Gemstones: Mineral Gemstones — U.S. Geological Survey: https://pubs.usgs.gov/gip/gemstones/mineral.html

## Specimen photograph

- Image: https://lithomap.app/_delivery/identification/minerals/epidote.webp
- Description: Radiating dark green-black epidote crystals with minor clear to white quartz
- Creator: Darla Sondrol
- License: CC0 1.0 — https://creativecommons.org/publicdomain/zero/1.0/
- Source record: https://commons.wikimedia.org/wiki/File:Epidote_(GeoDIL_number_-_1025).jpg

This reference supports preliminary field identification. It is not a laboratory determination, appraisal, hazard assessment, proof of origin, or statement of land ownership, legal access, or collecting permission.