metamorphic
Likely tumbled greenstone (identity uncertain)
Greenstone: metamorphosed mafic volcanic rock, commonly composed of chlorite, actinolite, and epidote
AI-generated identification · may be incorrectSmall, smooth, dark olive-green pebble with a subdued luster; hardness and composition cannot be determined reliably from the image. Greenstone is typically fine-grained and lacks visible crystal faces.
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Physical properties
Small, smooth, dark olive-green pebble with a subdued luster; hardness and composition cannot be determined reliably from the image. Greenstone is typically fine-grained and lacks visible crystal faces.
Formation & geological history
Usually forms when basalt or related mafic rock is altered by low-grade metamorphism and hydrothermal fluids; its age depends on the source rock and cannot be inferred from this specimen.
Uses & applications
Tumbled pieces are used in jewelry, crafts, and collections; larger greenstone bodies have limited construction use.
Geological facts
“Greenstone” is a descriptive field term for several green, altered rocks, not one uniquely defined mineral or rock composition.
Field identification & locations
A green color and fine-grained texture are suggestive but not diagnostic; the image alone cannot distinguish greenstone from other dark-green stones. A hardness or mineral test and closer inspection would be needed.
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