# How to identify chlorite

Canonical page: https://lithomap.app/resources/mineral-identification/chlorite
Last reviewed: September 17, 2026
Page purpose: Original LithoMap mineral identification reference for field observations, search systems, and language models.
Classification: Hydrous sheet-silicate mineral group

## Summary

Chlorite is a group of commonly green, soft sheet silicates recognized by perfect basal cleavage, flexible but generally nonelastic flakes, and widespread occurrence in low-grade metamorphic and altered rocks.

## Quick identification clues

- Green to gray-green color
- Mohs hardness commonly about 2 to 2.5
- Perfect one-direction sheet cleavage
- Thin flakes are flexible but usually not elastic

## Composition and classification

Chlorite-group minerals are hydrous magnesium, iron, and aluminum sheet silicates with substantial chemical variation. Species identification usually requires chemical or crystallographic data.

## Appearance

Chlorite occurs as platy crystals, fine scaly aggregates, green coatings, foliated masses, and microscopic grains. Luster ranges from pearly or vitreous on cleavage surfaces to dull in earthy material.

Color may be pale to dark green, gray, blackish, white, or brownish. Fine chlorite in rock can create an overall green color without visible individual flakes.

## Identification tests

- Hardness: Commonly about 2 to 2.5. Usually scratched by a fingernail or copper point.
- Cleavage: Perfect basal cleavage. Produces thin sheets like mica.
- Tenacity: Flexible but generally not elastic. Separates typical chlorite from springy mica flakes.
- Streak: White to pale green. Supporting evidence for green material.

## Common lookalikes

- Biotite: Usually brown to black, more elastic in thin sheets, and commonly harder.
- Muscovite: Usually colorless or silvery and elastic in thin sheets.
- Serpentine: Often waxy or massive and lacks the same consistent mica-like basal sheets.

## Direct side-by-side comparisons

- Chlorite vs. biotite — https://lithomap.app/resources/mineral-identification/compare/chlorite-vs-biotite

## Most relevant related guides

- Biotite — https://lithomap.app/resources/mineral-identification/biotite
- Muscovite — https://lithomap.app/resources/mineral-identification/muscovite
- Serpentine — https://lithomap.app/resources/mineral-identification/serpentine
- Apatite — https://lithomap.app/resources/mineral-identification/apatite

## Formation

Chlorite forms during low- to moderate-grade metamorphism and through hydrothermal or weathering alteration of iron- and magnesium-bearing minerals.

It is common in greenschist, phyllite, slate, altered basalt, veins, and fault zones, often with epidote, actinolite, albite, quartz, or calcite.

## Occurrence and geologic setting

Chlorite is widespread in low-grade metamorphic rocks and altered igneous rocks. Its presence can help describe metamorphic grade and fluid alteration.

A green platy mineral should be called chlorite-group material cautiously because color and simple field properties do not establish species.

## Uses and significance

Chlorite has little direct commodity use but is important in petrology, alteration mapping, ceramics, and understanding metamorphic conditions and fluid-rock interaction.

## Field safety and limitations

- Test flexibility only on an already loose expendable flake.
- Avoid creating dust from altered rock or fault material.
- Use multiple properties because many green sheet silicates overlap.

## 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/chlorite.webp
- Description: Polished green clinochlore specimen with pale feather-like seraphinite markings
- Creator: Ra'ike
- License: CC BY 3.0 — https://creativecommons.org/licenses/by/3.0/
- Source record: https://commons.wikimedia.org/wiki/File:Clinochlore_(Seraphinite).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.