metamorphic
Dark green cabochon, likely serpentine or nephrite jade
Serpentine-group minerals, commonly antigorite/lizardite; possible nephrite (microcrystalline tremolite-actinolite)
AI-generated identification · may be incorrectOpaque to translucent dark green, waxy to vitreous luster, rounded polished cabochon; serpentine hardness 2.5–4 Mohs, nephrite 6–6.5. Specific gravity is typically 2.5–3.1; crystal structure is usually too fine-grained to see and cleavage is indistinct.
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Physical properties
Opaque to translucent dark green, waxy to vitreous luster, rounded polished cabochon; serpentine hardness 2.5–4 Mohs, nephrite 6–6.5. Specific gravity is typically 2.5–3.1; crystal structure is usually too fine-grained to see and cleavage is indistinct.
Formation & geological history
Serpentine forms when ultramafic rocks hydrate during metamorphism; nephrite forms through metamorphic alteration of magnesium-rich rocks. Precise age and identity cannot be determined from the photograph.
Uses & applications
Used for cabochons, beads, carvings, and ornamental objects; nephrite is valued for toughness and jewelry use, while common serpentine is inexpensive decorative material.
Geological facts
The image appears to show a polished, possibly drilled cabochon with cloudy dark-green color and lighter veining. It may also be dyed or treated, so visual identification is provisional.
Field identification & locations
Test hardness cautiously: glass-scratching ability suggests nephrite rather than serpentine; a refractometer, specific-gravity test, and microscopic examination are more reliable. Common sources include China, New Zealand, Canada, Russia, and the United States.
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