metamorphic
Polished greenstone pebble
Nephrite jade (compact tremolite–actinolite amphibole), possibly serpentine
AI-generated identification · may be incorrectOpaque olive-green to brown, smoothly polished, vitreous-to-waxy luster; typically Mohs 6–6.5 for nephrite (serpentine is softer, 2.5–5.5), with no visible cleavage and a tough, fibrous microcrystalline structure.
Identified More metamorphic →
Explore Polished greenstone pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Opaque olive-green to brown, smoothly polished, vitreous-to-waxy luster; typically Mohs 6–6.5 for nephrite (serpentine is softer, 2.5–5.5), with no visible cleavage and a tough, fibrous microcrystalline structure.
Formation & geological history
Nephrite forms when magnesium-rich rocks undergo metamorphism and fluids promote amphibole growth, commonly in subduction-zone mélanges; source rocks may be Paleozoic to Cenozoic. The exact specimen cannot be dated from the image.
Uses & applications
Used for carvings, beads, cabochons, ornaments, and historically tools; serpentine is a less valuable jade substitute. Value is mainly determined by color, translucency, texture, size, and verified identity.
Geological facts
The rounded shape and high polish indicate a tumbled or cabochon-cut specimen. Nephrite is exceptionally tough because its interlocking amphibole fibers resist breaking.
Field identification & locations
Common sources include British Columbia, New Zealand, China, Taiwan, Russia, Wyoming, and California. Test with a steel knife cautiously: true nephrite generally resists scratching, while serpentine may scratch; definitive identification requires refractive index, specific gravity, or laboratory testing.
More like this
