metamorphic
Polished greenstone, likely serpentine
Serpentinite (serpentine-group minerals, chiefly antigorite/lizardite; commonly with magnetite or chlorite)
AI-generated identification · may be incorrectOpaque olive- to moss-green, waxy to subvitreous luster, fine-grained and massive with dark veining or mottling. Hardness is typically 2.5–4 Mohs, with no obvious cleavage; specific gravity is about 2.5–2.6. The smoothly polished, rounded form is a worked/tumbled specimen.
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Physical properties
Opaque olive- to moss-green, waxy to subvitreous luster, fine-grained and massive with dark veining or mottling. Hardness is typically 2.5–4 Mohs, with no obvious cleavage; specific gravity is about 2.5–2.6. The smoothly polished, rounded form is a worked/tumbled specimen.
Formation & geological history
Serpentinite forms when ultramafic mantle rocks such as peridotite are hydrated during metamorphism, commonly along ancient oceanic crust and tectonic boundaries. Precise age cannot be determined from the photograph; deposits range from Precambrian to modern tectonic settings.
Uses & applications
Used for carvings, beads, ornamental stone, countertops, and decorative objects. Common material is generally inexpensive, though exceptionally patterned or culturally significant greenstone can be valuable.
Geological facts
Its appearance can overlap with nephrite jade, bowenite, and chlorite-rich rocks; visual identification alone is not definitive. Serpentine may contain trace chrysotile asbestos, so avoid cutting, drilling, or generating dust without proper testing and controls.
Field identification & locations
Common localities include California, New Zealand, Italy, Canada, Afghanistan, and Russia. Field clues include a soft, waxy feel, green color, dark magnetite streaks, and scratching by a steel knife; jade is substantially harder and tougher. Estimated value: $5–$30 for a typical polished piece; $30–$150 if unusually large, attractive, or verified as quality bowenite/nephrite.
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