metamorphic

Likely amphibolite

Amphibolite, composed chiefly of hornblende and plagioclase feldspar

AI-generated identification · may be incorrect

Dark greenish-gray, coarse and unevenly crystalline with a rough, weakly foliated texture; likely Mohs hardness 5–6. Mineral identification and exact composition cannot be confirmed from the image alone.

Identified September 29, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when basaltic or gabbroic rock is metamorphosed under moderate-to-high heat and pressure, commonly during mountain building. Its age depends on the region and cannot be determined visually.

Uses & applications

Used locally as crushed stone, road aggregate, and dimension stone; attractive pieces may be kept as geological specimens.

Geological facts

Amphibolite’s dark color commonly comes from amphibole minerals such as hornblende, often mixed with pale feldspar.

Field identification & locations

Look for a dense, dark rock with visible interlocking crystals and possible aligned amphibole grains; it occurs in metamorphic belts worldwide. A close inspection or mineral testing would be needed to distinguish it from other dark metamorphic rocks.