metamorphic
Polished dark green stone, likely nephrite jade or serpentine
Nephrite jade: tremolite–actinolite amphibole, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂; possible serpentine: Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectDark green, opaque, smooth polished surface with waxy to greasy luster; nephrite hardness ~6–6.5 Mohs, serpentine ~2.5–5.5. Both are microcrystalline and lack visible crystal faces; nephrite is notably tough and compact.
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Physical properties
Dark green, opaque, smooth polished surface with waxy to greasy luster; nephrite hardness ~6–6.5 Mohs, serpentine ~2.5–5.5. Both are microcrystalline and lack visible crystal faces; nephrite is notably tough and compact.
Formation & geological history
Nephrite forms through metamorphism of magnesium-rich rocks, commonly in serpentinite-associated zones; serpentine forms by hydration of ultramafic mantle rocks. Exact age and identity cannot be determined from the photograph.
Uses & applications
Used for carvings, beads, cabochons, ornamental objects, and jewelry; nephrite has substantial cultural and artistic importance.
Geological facts
The rounded specimen appears tumbled or cabochon-polished. A hardness test, density measurement, and refractive-index or Raman analysis are needed to distinguish jade from serpentine or dyed material.
Field identification & locations
Common sources include British Columbia, Wyoming, New Zealand, Siberia, China, and Australia. Look for exceptional toughness, even color, fibrous texture, and high density in nephrite; avoid scratching valuable pieces.
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