metamorphic
Likely polished serpentine or nephrite jade pebble
Serpentine-group minerals, commonly antigorite/lizardite; possibly nephrite jade (interlocking tremolite-actinolite)
AI-generated identification · may be incorrectDark olive-green, mottled, polished, and opaque to slightly translucent with a waxy-to-greasy luster; serpentine hardness is 2.5–4 Mohs, while nephrite is 6–6.5. Exact identification requires hardness, specific-gravity, and instrumental testing.
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Physical properties
Dark olive-green, mottled, polished, and opaque to slightly translucent with a waxy-to-greasy luster; serpentine hardness is 2.5–4 Mohs, while nephrite is 6–6.5. Exact identification requires hardness, specific-gravity, and instrumental testing.
Formation & geological history
Serpentine forms when ultramafic rocks are hydrated during low-temperature metamorphism; nephrite forms by metasomatic metamorphism of magnesium-rich rocks. These processes range from ancient Precambrian terrains to younger orogenic belts.
Uses & applications
Used for beads, carvings, cabochons, and ornamental objects; serpentine is also a decorative building stone, while nephrite has substantially higher jewelry and carving value.
Geological facts
The smooth oval shape indicates tumbling or natural water wear. Green color alone cannot reliably distinguish jade from common serpentine, bowenite, greenstone, or dyed materials.
Field identification & locations
Common sources include New Zealand, China, Canada, Russia, Afghanistan, and the United States. Check for uniform polish, fibrous toughness, translucency, and an unusually cool feel; a gemological test is needed for confirmation.
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