igneous
Unidentified greenish-gray rock fragment
Tentatively altered basalt or basaltic volcanic rock; mineral identification requires testing
AI-generated identification · may be incorrectFine- to medium-grained, dull earthy luster, pale green-gray color, and irregular fracture. Likely hardness about 5–6 Mohs, with abundant altered silicate minerals; crystal structure and specific gravity cannot be confirmed visually.
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Physical properties
Fine- to medium-grained, dull earthy luster, pale green-gray color, and irregular fracture. Likely hardness about 5–6 Mohs, with abundant altered silicate minerals; crystal structure and specific gravity cannot be confirmed visually.
Formation & geological history
Possibly weathered or hydrothermally altered basalt formed from rapidly cooled mafic lava, generally ranging from recent to Precambrian in age depending on locality. The granular surface may reflect alteration or weathering.
Uses & applications
Common basalt is used as aggregate, roadstone, riprap, and occasionally decorative stone; this tiny unprovenanced fragment has negligible commercial value.
Geological facts
Green coloration may indicate chlorite, epidote, or serpentine replacing original pyroxene and feldspar. It could also be a metamorphic or sedimentary fragment, so a confident name cannot be assigned from the photograph alone.
Field identification & locations
Look for dark mafic coloration, fine grains, weak magnetism, and hardness sufficient to scratch glass; a streak, density, magnet, and fresh broken surface would help distinguish basalt from greenstone or serpentinite. Common in volcanic and altered-oceanic terrains.
