metamorphic
Polished river stone, likely serpentinite or altered ultramafic rock
Serpentinite-dominant rock; chiefly serpentine-group minerals, commonly with magnetite, talc, and carbonate
AI-generated identification · may be incorrectHardness typically 2.5–4 Mohs; rounded and polished, mottled olive-green, brown, gray, and rusty red, with a dull to waxy luster. The visible veining and weathered iron staining are consistent with serpentinization, though the photograph cannot confirm composition.
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Physical properties
Hardness typically 2.5–4 Mohs; rounded and polished, mottled olive-green, brown, gray, and rusty red, with a dull to waxy luster. The visible veining and weathered iron staining are consistent with serpentinization, though the photograph cannot confirm composition.
Formation & geological history
Formed when mantle-derived peridotite was altered by water, commonly along tectonic plate boundaries and fault zones; individual stones are later rounded by river transport. The alteration may range from Paleozoic to modern geological settings depending on locality.
Uses & applications
Used as a decorative stone, carving material, landscaping aggregate, and collector specimen; high-quality patterned serpentinite may be used for ornamental slabs and small carvings.
Geological facts
Serpentinite often contains magnetite, making some pieces weakly magnetic, and can show a distinctive slick, waxy feel. Green color commonly results from serpentine minerals rather than copper.
Field identification & locations
Look for low density, waxy surfaces, green-brown mottling, curved veins, and possible weak magnetism; a hardness or streak test and locality information would improve identification. Common in ophiolite belts and serpentinite-bearing mountain regions.
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