metamorphic

Dark metamorphic rock, possibly amphibolite

Amphibolite (tentative; commonly hornblende and plagioclase)

AI-generated identification · may be incorrect

Dark gray-green, coarse to medium-grained, with a rough, mottled surface and weakly visible mineral alignment. Amphibole hardness is about 5–6 on the Mohs scale; the image does not allow reliable identification of luster, cleavage, or specific gravity.

Identified October 4, 2026More metamorphic →

Explore Dark metamorphic rock, possibly amphibolite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Amphibolite forms when basaltic or gabbroic rocks are metamorphosed under moderate-to-high heat and pressure. Such rocks occur in many Precambrian and younger metamorphic belts; the specimen’s age cannot be determined from the photo.

Uses & applications

Amphibolite is used locally as crushed stone, aggregate, and dimension stone; attractive pieces may be collected or polished.

Geological facts

The pictured specimen is consistent with a dark, amphibole-rich rock, but other dark rocks—such as basalt or hornblende-rich gneiss—can look similar.

Field identification & locations

A firm identification requires examining fresh surfaces and mineral grains; amphibolite commonly contains visible dark hornblende and lighter plagioclase. Found in metamorphic terrains worldwide.