igneous
Likely basaltic or mafic metamorphic rock
Fine-grained mafic rock, probably basalt or altered basalt; composition mainly plagioclase and pyroxene, possibly chlorite/epidote
AI-generated identification · may be incorrectDark gray-green, fine-grained, dull to weakly waxy luster, massive texture, and no obvious cleavage; estimated Mohs hardness 5–6 and specific gravity about 2.8–3.1. The green coloration suggests alteration or low-grade metamorphism.
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Physical properties
Dark gray-green, fine-grained, dull to weakly waxy luster, massive texture, and no obvious cleavage; estimated Mohs hardness 5–6 and specific gravity about 2.8–3.1. The green coloration suggests alteration or low-grade metamorphism.
Formation & geological history
Likely formed from rapidly cooled mafic lava, then altered by circulating fluids or low-grade metamorphism; exact age and origin cannot be determined from the photograph. Common in volcanic provinces, oceanic crust, and greenstone belts.
Uses & applications
Basalt is used as crushed aggregate, roadstone, riprap, and occasionally dimension stone; attractive polished pieces may be collected, though this specimen appears ordinary.
Geological facts
Its compact, fine texture and dark green-gray color are consistent with basalt, but the image cannot distinguish it confidently from greenstone or fine-grained amphibolite.
Field identification & locations
Look for a uniform fine grain, high density, dull dark color, and possible tiny pale plagioclase crystals; a streak, magnetism test, fresh break, and thin section would improve identification. Common worldwide in volcanic and metamorphic terrains.
