metamorphic

Tumbled greenstone (likely serpentine or nephrite-like material)

Serpentine-group minerals, commonly antigorite/lizardite; possibly nephrite jade (actinolite-tremolite)

AI-generated identification · may be incorrect

Olive-green to yellow-green, smoothly polished, opaque, and waxy to dull luster; typically Mohs 2.5–4 for serpentine or 6–6.5 for nephrite. The rounded shape is human-tumbled; exact identification requires hardness, streak, density, and microscopic testing.

Identified August 14, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentine or nephrite-like material)
Scientific name: Serpentine-group minerals, commonly antigorite/lizardite; possibly nephrite jade (actinolite-tremolite)
Category: metamorphic
Identified: August 14, 2026
Method: Standard

AI Estimated Value

$2–$15 as a common tumbled serpentine stone; approximately $20–$200+ if verified as quality nephrite jade.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Serpentine forms when ultramafic mantle rocks undergo hydration and metamorphism; nephrite forms by metamorphic alteration involving magnesium-rich rocks. These materials range from ancient Precambrian to younger geological ages depending on locality.

Uses & applications

Used as decorative tumbled stone, carvings, ornamental objects, and—if confirmed nephrite—as jewelry and tools; serpentine is mainly a collector and architectural material.

Geological facts

The mottled olive coloration and waxy polish are characteristic of common serpentine-bearing stones, but appearance alone cannot distinguish serpentine from jade or other green rocks.

Field identification & locations

Look for black-green mottling, low-to-moderate weight, waxy texture, and variable translucency; a steel scratch test can separate softer serpentine from harder nephrite, though it may damage the specimen. Common sources include California, New Zealand, Canada, Russia, and China.