metamorphic
Tumbled greenish-gray stone, likely serpentinite or altered basalt
Probable serpentinite (serpentine-group minerals), possibly chlorite-/epidote-bearing basalt
AI-generated identification · may be incorrectTypically Mohs 3–5.5; mottled olive-green, gray, and tan with a dull to waxy luster, fine-grained texture, and no visible crystal faces or cleavage. The rounded shape indicates tumbling or natural water wear.
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Physical properties
Typically Mohs 3–5.5; mottled olive-green, gray, and tan with a dull to waxy luster, fine-grained texture, and no visible crystal faces or cleavage. The rounded shape indicates tumbling or natural water wear.
Formation & geological history
Serpentinite forms when ultramafic mantle rocks are hydrated during metamorphism, commonly in oceanic crust and tectonic fault zones; altered basalt is a possible alternative. Exact age and identity cannot be determined from the photograph alone.
Uses & applications
Usually sold as a decorative or lapidary stone and used for carvings, cabochons, and polished objects; serpentinite has also been used as ornamental building stone.
Geological facts
The specimen appears to be a polished/tumbled geological material rather than a fresh unaltered rock. A hardness test, streak, specific gravity, and examination of a fresh surface would substantially improve identification.
Field identification & locations
Common serpentinite occurs in California, Vermont, Italy, New Zealand, and many ophiolite belts; it is identified by green mottling, waxy feel, and relatively low hardness. Avoid assuming it is jade without testing—serpentinite is softer and less dense.
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