metamorphic
Tumbled greenstone (likely serpentine or nephrite jade)
Serpentine-group mineral aggregate, or possibly nephrite (interlocking tremolite–actinolite amphibole)
AI-generated identification · may be incorrectHardness is approximately 2.5–4 for serpentine or 6–6.5 for nephrite; olive-green, opaque, smoothly polished, with waxy to greasy luster and no visible crystal faces. The rounded shape indicates tumbling; identification cannot be certain from an image alone.
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Physical properties
Hardness is approximately 2.5–4 for serpentine or 6–6.5 for nephrite; olive-green, opaque, smoothly polished, with waxy to greasy luster and no visible crystal faces. The rounded shape indicates tumbling; identification cannot be certain from an image alone.
Formation & geological history
Serpentine forms when ultramafic mantle rocks undergo hydrothermal alteration, while nephrite forms by metamorphic replacement in tectonic zones; ages vary from ancient Precambrian to modern geologic settings.
Uses & applications
Used for carvings, beads, ornaments, and decorative stone; genuine nephrite has greater jewelry and collector value than common serpentine.
Geological facts
Green color and waxy polish are characteristic, but many materials are sold broadly as “greenstone.” Density, hardness, and microscopic examination best distinguish it from jadeite, serpentine, and dyed stones.
Field identification & locations
Common sources include New Zealand, China, Russia, Canada, the United States, and Central Asia. Test cautiously: nephrite resists scratching by steel, whereas serpentine is usually scratched more easily; laboratory testing is recommended.
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