# How to identify olivine

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

## Summary

Olivine is an olive-green to yellow-green rock-forming silicate, usually granular, hard, glassy, and lacking good cleavage; gem-quality material is called peridot.

## Quick identification clues

- Olive, yellow-green, or brownish green
- Glassy luster
- Mohs hardness about 6.5 to 7
- Granular habit with poor cleavage and uneven fracture

## Composition and classification

Olivine is a solid-solution group between magnesium-rich forsterite and iron-rich fayalite. Most common rock-forming grains lie between those end members.

## Appearance

Olivine often occurs as small glassy green grains scattered through dark basalt or concentrated in coarse ultramafic rock.

Weathering and hydrothermal alteration can replace it with reddish-brown iron oxides, clay, carbonate, or green serpentine minerals. Fresh surfaces are important.

## Identification tests

- Hardness: 6.5 to 7. Fresh grains scratch glass.
- Streak: White. Often difficult to obtain because grains are hard.
- Cleavage: Poor or indistinct. Breaks unevenly rather than into repeated flat sheets.
- Luster: Vitreous. Best seen on fresh green grains.

## Common lookalikes

- Epidote: Often pistachio green with one good cleavage and commonly more elongate crystals.
- Serpentine: Usually softer, waxier, and may be fibrous or massive rather than hard glassy grains.
- Green garnet: Garnet lacks cleavage too but commonly forms more equant crystal shapes and can be denser.

## Direct side-by-side comparisons

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

## Most relevant related guides

- Epidote — https://lithomap.app/resources/mineral-identification/epidote
- Garnet — https://lithomap.app/resources/mineral-identification/garnet
- Serpentine — https://lithomap.app/resources/mineral-identification/serpentine
- Augite — https://lithomap.app/resources/mineral-identification/augite

## Formation

Olivine crystallizes early from many mafic and ultramafic magmas and is a major mineral in Earth’s upper mantle.

It reaches the surface in basalt, mantle xenoliths, and tectonically exposed ultramafic rocks. It weathers comparatively quickly under many surface conditions.

## Occurrence and geologic setting

Olivine is common in basalt, gabbro, peridotite, and mantle xenoliths. Gem peridot requires unusual clarity, color, and crystal size.

Loose green grains in volcanic sand may include olivine, pyroxene, glass, or several minerals; magnification and testing improve confidence.

## Uses and significance

Olivine is used as foundry sand, refractory material, slag conditioner, and gemstone. It is also studied for potential carbon-mineralization applications.

## Field safety and limitations

- Avoid fibrous alteration products in unknown ultramafic rock; do not create dust.
- Color alone cannot distinguish olivine from other green silicates.
- Gem quality and value cannot be established from a field identification.

## 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/olivine.webp
- Description: Yellow-green olivine crystal specimen in dark matrix
- Creator: Robert M. Lavinsky
- License: CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/
- Source record: https://commons.wikimedia.org/wiki/File:Olivine-213076.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.