metamorphic
Tumbled greenstone pebble
Likely serpentinite or greenstone; exact identification requires testing
AI-generated identification · may be incorrectDark olive-green, rounded and polished/tumbled, with a dull to waxy luster and subtle mottling. Likely Mohs hardness about 3–6 depending on composition; massive, non-crystalline appearance and no obvious cleavage.
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Physical properties
Dark olive-green, rounded and polished/tumbled, with a dull to waxy luster and subtle mottling. Likely Mohs hardness about 3–6 depending on composition; massive, non-crystalline appearance and no obvious cleavage.
Formation & geological history
Possible serpentinite formed by hydrothermal alteration of ultramafic rock, or a chlorite/epidote-rich metamorphic greenstone. Such rocks commonly formed during ancient tectonic activity; the specimen’s age and locality cannot be determined visually.
Uses & applications
Used as a decorative tumbled stone, carving material, or lapidary specimen; some greenstones are used for ornaments and tools. This small piece generally has modest commercial value.
Geological facts
The term “greenstone” is descriptive rather than a single mineral name. Serpentinite may contain fibrous minerals and should not be cut or aggressively abraded without appropriate dust protection.
Field identification & locations
Check streak, hardness, density, and translucency: serpentinite is commonly softer and waxier, while epidote/chlorite greenstone is harder and denser. Common sources include tectonic belts in California, New Zealand, Italy, Canada, and the Appalachians.
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