metamorphic

Dark, coarse-grained rock fragment (possibly amphibolite or gabbro)

Uncertain from the photo; likely amphibolite (hornblende-rich metamorphic rock) or a mafic igneous rock such as gabbro

AI-generated identification · may be incorrect

Dark gray-green with pale mineral grains and a rough, granular texture; likely composed of amphibole and plagioclase if amphibolite, or pyroxene and plagioclase if gabbro. Hardness and cleavage cannot be reliably determined from the image.

Identified September 25, 2026More metamorphic →

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Physical properties

Formation & geological history

If amphibolite, it formed when basaltic rock was metamorphosed under heat and pressure; if gabbro, it crystallized slowly underground from magma. Age and formation location cannot be established visually.

Uses & applications

Comparable rocks are used as crushed aggregate and building stone; this small fragment has little commercial value but may interest a collector.

Geological facts

Amphibolite and gabbro can look similar in a small, weathered fragment; mineral identification or a fresh surface would help distinguish them.

Field identification & locations

The specimen is dark, visibly granular, and appears to contain light and dark minerals. A hand-lens view and hardness or streak tests can narrow the identification; such rocks occur in ancient metamorphic belts and mafic intrusions worldwide.