metamorphic

Amphibolite

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

AI-generated identification · may be incorrect

Dark gray-green, coarse- to medium-grained, with a sparkly crystalline texture. Typical minerals have Mohs hardness about 5–6; amphibole crystals are prismatic and commonly show two cleavage directions near 60° and 120°.

Identified October 8, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when basalt or gabbro undergoes medium- to high-grade regional metamorphism. Its age depends on the source rock and metamorphic event; the image alone cannot establish it.

Uses & applications

Used as crushed stone, aggregate, and occasionally decorative building stone; attractive specimens may be collected, but it is rarely used as a gemstone.

Geological facts

The visible glitter and dark, elongate grains are consistent with amphibole-rich rock, though a photograph cannot confirm the exact identification.

Field identification & locations

Look for dark amphibole grains intergrown with lighter feldspar and a tough, crystalline texture; amphibolite occurs in metamorphic belts worldwide. A small common fragment typically has little commercial value.