metamorphic
Tumbled greenstone, likely nephrite jade
Nephrite jade (interlocking tremolite–actinolite amphibole; Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂)
AI-generated identification · may be incorrectHardness about 6–6.5 Mohs; opaque dark green with black inclusions, greasy-to-waxy luster, and a dense fibrous crystal structure. No visible cleavage; toughness is exceptionally high. The polished, rounded form indicates tumbling.
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Physical properties
Hardness about 6–6.5 Mohs; opaque dark green with black inclusions, greasy-to-waxy luster, and a dense fibrous crystal structure. No visible cleavage; toughness is exceptionally high. The polished, rounded form indicates tumbling.
Formation & geological history
Forms when magnesium-rich rocks undergo metamorphism and fluid alteration, commonly in serpentinite-associated zones. Important deposits occur in New Zealand, British Columbia, Siberia, China, and Wyoming; ages vary widely by locality.
Uses & applications
Used for carvings, beads, cabochons, ornaments, and traditional tools; high-quality material is valued in jewelry and cultural art.
Geological facts
Nephrite is technically an amphibole aggregate rather than a single crystal. Its toughness historically made it useful for axes and blades, and it is one of the two materials called jade.
Field identification & locations
Identify by its dense green color, black veining, waxy polish, and resistance to scratching; quartz should not scratch genuine nephrite easily. Definitive identification requires specific gravity, refractive index, or laboratory testing.
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