metamorphic
Polished greenstone pebble (likely serpentine or chlorite-rich stone)
Serpentine-group minerals, commonly antigorite/lizardite; possible chlorite-rich metamorphic rock
AI-generated identification · may be incorrectDark green to black, mottled, with a waxy to subdued vitreous luster and rounded polished surface; likely Mohs 2.5–4, lacking visible cleavage. Exact identification requires hardness, streak, density, and mineralogical testing.
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Physical properties
Dark green to black, mottled, with a waxy to subdued vitreous luster and rounded polished surface; likely Mohs 2.5–4, lacking visible cleavage. Exact identification requires hardness, streak, density, and mineralogical testing.
Formation & geological history
Typically formed by low- to moderate-temperature metamorphic hydration of ultramafic rocks, especially mantle-derived peridotite; deposits range from ancient Precambrian belts to younger ophiolites. The specimen appears human-polished or naturally water-rounded.
Uses & applications
Used as ornamental stone, carvings, beads, cabochons, and small collectible pebbles; massive serpentine has also been used decoratively in architecture. This small piece has little commercial value unless unusually attractive or analytically confirmed as a rarer greenstone.
Geological facts
Serpentine can resemble jade, but it is generally softer and less dense; some varieties contain magnetite, producing dark specks or weak magnetism. The image alone cannot distinguish serpentine from chlorite, nephrite, or other dark green rocks.
Field identification & locations
Look for a greasy/waxy green surface, low hardness, and occasional black magnetite grains; a steel nail may scratch it, while jade generally resists scratching. Common sources include California, New Zealand, Italy, Canada, and ophiolite belts worldwide.
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