metamorphic

Amphibolite

Amphibolite, composed mainly of amphibole (commonly hornblende) and plagioclase feldspar

AI-generated identification · may be incorrect

Dark gray-green, coarse crystalline, with a granular to weakly foliated texture and vitreous-to-dull luster. Typical constituent minerals have Mohs hardness around 5–6; rock density is commonly about 2.9–3.2 g/cm³. Exact identification and properties cannot be confirmed from the photo alone.

Identified October 3, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when basaltic or gabbroic rocks undergo medium- to high-grade metamorphism, often during mountain building; it occurs across a wide range of geological ages.

Uses & applications

Used as crushed stone, aggregate, and sometimes dimension stone; attractive polished pieces may be used decoratively.

Geological facts

Its dark amphibole minerals and lighter feldspar commonly create a speckled appearance; some amphibolites preserve evidence of ancient oceanic crust.

Field identification & locations

Look for interlocking dark amphibole and pale feldspar grains, often with weak alignment. Found in metamorphic belts worldwide; the pictured specimen is an approximate visual identification.