metamorphic
Polished serpentine (likely antigorite or bowenite)
Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectDark olive-green, waxy to greasy luster with pale mottling; typically massive rather than visibly crystalline, Mohs hardness 2.5–4, poor cleavage, and specific gravity about 2.5–2.6. The rounded, glossy surface indicates a polished or tumbled specimen.
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Physical properties
Dark olive-green, waxy to greasy luster with pale mottling; typically massive rather than visibly crystalline, Mohs hardness 2.5–4, poor cleavage, and specific gravity about 2.5–2.6. The rounded, glossy surface indicates a polished or tumbled specimen.
Formation & geological history
Forms when magnesium-rich ultramafic rocks such as peridotite hydrate during low-temperature metamorphism, commonly in ancient oceanic crust and subduction zones. Serpentinization occurs from the Precambrian to the present.
Uses & applications
Used as ornamental stone, carvings, cabochons, beads, and architectural material; historically marketed as “new jade” or bowenite. It is generally less durable than true jade.
Geological facts
Commonly contains magnetite, producing dark specks and sometimes weak magnetism; asbestos-form serpentine varieties can occur in the same rocks, though this polished piece is not identifiable as hazardous from the image alone.
Field identification & locations
Identify by its olive-green color, waxy feel, mottled pattern, low hardness, and possible magnetism; common localities include California, Vermont, Italy, New Zealand, Russia, and Afghanistan. Similar dark green rocks may be chlorite-rich schist or nephrite, requiring testing for certainty.
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