metamorphic
Polished green-and-white stone, likely serpentine or nephrite jade
Serpentine-group minerals, commonly antigorite/lizardite; possible nephrite (interlocking actinolite–tremolite)
AI-generated identification · may be incorrectHardness is approximately 3–5.5 Mohs for serpentine or 6–6.5 for nephrite; the specimen is rounded and polished, dark green with cream-gray areas and a waxy to vitreous luster. Exact identification requires hardness, streak, density, and ideally microscopy or spectroscopy.
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Physical properties
Hardness is approximately 3–5.5 Mohs for serpentine or 6–6.5 for nephrite; the specimen is rounded and polished, dark green with cream-gray areas and a waxy to vitreous luster. Exact identification requires hardness, streak, density, and ideally microscopy or spectroscopy.
Formation & geological history
Serpentine forms when ultramafic rocks undergo low-temperature hydration; nephrite forms through metamorphism of magnesium-rich rocks. These processes range from ancient Precambrian to younger tectonic events.
Uses & applications
Used as ornamental stone, carvings, beads, cabochons, and sometimes architectural material; nephrite-quality material is valued for jewelry and sculpture.
Geological facts
Green color commonly comes from iron and chromium. Serpentine is generally softer and less tough than nephrite, while nephrite has a distinctive fibrous, exceptionally tough texture.
Field identification & locations
Common sources include California, Oregon, British Columbia, New Zealand, China, and Central Asia. A steel knife may scratch serpentine but usually not nephrite; avoid relying on color alone because polished serpentine is frequently sold as jade.
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