metamorphic
Polished green stone, possibly serpentine or nephrite jade
Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; alternatively nephrite, a tremolite–actinolite aggregate
AI-generated identification · may be incorrectDark mottled green, waxy to subvitreous luster, opaque, and likely fine-grained with no visible crystal faces; hardness is approximately Mohs 3–5.5 for serpentine or 6–6.5 for nephrite, with poor cleavage and specific gravity around 2.5–3.0.
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Physical properties
Dark mottled green, waxy to subvitreous luster, opaque, and likely fine-grained with no visible crystal faces; hardness is approximately Mohs 3–5.5 for serpentine or 6–6.5 for nephrite, with poor cleavage and specific gravity around 2.5–3.0.
Formation & geological history
Serpentine forms when ultramafic mantle rocks undergo hydration during metamorphism; nephrite forms through metamorphic alteration of magnesium-rich rocks. Ages vary widely by locality, commonly Paleozoic or younger.
Uses & applications
Used as ornamental stone, carvings, beads, cabochons, and occasionally architectural material; nephrite-quality material can be valuable.
Geological facts
The image is insufficient for a definitive distinction between serpentine, nephrite, chlorite-rich rock, or another green metamorphic stone. A steel scratch test and specific-gravity measurement can help separate them.
Field identification & locations
Common sources include California, New Zealand, British Columbia, Russia, China, and Guatemala. Serpentine scratches relatively easily; nephrite resists scratching and has a notably tough, fibrous texture.
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