metamorphic

Greenstone cabochon

Likely serpentinite or chlorite-rich greenschist; exact identification requires testing

AI-generated identification · may be incorrect

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.

Identified August 16, 2026More metamorphic →

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Physical properties

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.