metamorphic
Greenstone pebble (identification uncertain from photo)
Greenstone, typically metamorphosed mafic rock composed of chlorite, actinolite, and epidote
AI-generated identification · may be incorrectRounded, dark green to gray-green pebble with pale mottling and a dull to slightly waxy surface. Greenstone is usually fine-grained, with hardness and density varying by mineral mix; exact properties cannot be determined visually here.
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Physical properties
Rounded, dark green to gray-green pebble with pale mottling and a dull to slightly waxy surface. Greenstone is usually fine-grained, with hardness and density varying by mineral mix; exact properties cannot be determined visually here.
Formation & geological history
Forms when basalt or other mafic rock is altered by low-grade metamorphism and gains green minerals. Such rocks occur in ancient metamorphic belts; the specimen’s age and provenance are unknown.
Uses & applications
Used as decorative stone, in carvings and jewelry, and historically for tools; value depends on composition, workmanship, and provenance.
Geological facts
“Greenstone” is a broad field term rather than one precise mineral or rock species.
Field identification & locations
The rounded shape suggests water transport, while its green color is consistent with chlorite- or actinolite-bearing rock. A scratch, streak, or mineralogical test would be needed for reliable identification; similar-looking serpentinite is another possibility.
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