metamorphic
Tumbled greenstone (likely nephrite jade)
Nephrite, an interlocking tremolite–actinolite amphibole aggregate; Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
AI-generated identification · may be incorrectOpaque olive-green, waxy to subtly greasy luster, rounded/tumbled surface with natural pits and veins; Mohs hardness 6–6.5, tough fibrous texture, no visible cleavage, specific gravity about 2.9–3.1. The image is consistent with nephrite, though serpentine or bowenite can look similar.
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Physical properties
Opaque olive-green, waxy to subtly greasy luster, rounded/tumbled surface with natural pits and veins; Mohs hardness 6–6.5, tough fibrous texture, no visible cleavage, specific gravity about 2.9–3.1. The image is consistent with nephrite, though serpentine or bowenite can look similar.
Formation & geological history
Forms when magnesium-rich rocks undergo metamorphism and hydration, commonly in serpentinite zones; deposits range from Paleozoic to younger tectonic settings. Common sources include New Zealand, British Columbia, Wyoming, Siberia, and China.
Uses & applications
Used for carvings, ornaments, beads, cabochons, tools, and decorative stone; high-quality translucent, evenly colored material is valuable in jewelry and art.
Geological facts
Nephrite is exceptionally resistant to breakage because of its felted amphibole fibers, making it tougher than many harder gemstones. New Zealand pounamu is a culturally significant nephrite variety.
Field identification & locations
Identify by its heavy feel, waxy green appearance, extreme toughness, and inability to scratch easily with a steel knife; distinguish from serpentine by greater toughness and usually higher density. The holes may be natural weathering or pore-like inclusions.
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