metamorphic
Greenstone cabochon
Likely serpentinite or chlorite-rich greenschist; exact identification requires testing
AI-generated identification · may be incorrectDark green-gray, opaque, fine-grained, with black mottling and a subdued waxy-to-dull luster; likely hardness about 3–5.5 Mohs, massive rather than visibly crystalline, with no obvious cleavage. The oval shape indicates polishing or tumbling.
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Physical properties
Dark green-gray, opaque, fine-grained, with black mottling and a subdued waxy-to-dull luster; likely hardness about 3–5.5 Mohs, massive rather than visibly crystalline, with no obvious cleavage. The oval shape indicates polishing or tumbling.
Formation & geological history
Probably formed by low- to medium-grade metamorphism or hydrothermal alteration of magnesium-rich ultramafic rock; ages vary widely by locality. Serpentinite commonly forms in oceanic crust and mantle rocks near tectonic boundaries.
Uses & applications
Used as a decorative stone, cabochon, bead, carving material, and occasionally architectural facing stone. This small specimen has modest jewelry value unless it proves to be a rarer jade variety.
Geological facts
Its appearance can overlap with nephrite jade, bowenite, chlorite schist, and serpentine. A hardness, specific-gravity, streak, and microscopic examination are needed for confident identification.
Field identification & locations
Commonly found in ophiolite belts, especially California, the Alps, New Zealand, and parts of Canada. Serpentinite is softer and often waxier than jade; avoid acid or scratch tests on polished surfaces.
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