metamorphic

Tumbled greenstone (likely serpentine or nephrite jade)

Serpentine-group minerals, chiefly antigorite/lizardite; possibly nephrite, a tremolite–actinolite amphibole aggregate

AI-generated identification · may be incorrect

Green, mottled, opaque, and waxy to subtly greasy luster; rounded and polished. Hardness is approximately Mohs 2.5–5.5 for serpentine or 6–6.5 for nephrite; no visible cleavage and typically massive, fine-grained texture.

Identified September 22, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentine or nephrite jade)
Scientific name: Serpentine-group minerals, chiefly antigorite/lizardite; possibly nephrite, a tremolite–actinolite amphibole aggregate
Category: metamorphic
Identified: September 22, 2026
Method: Standard

AI Estimated Value

About $2–$15 for a common tumbled serpentine pebble; roughly $10–$100+ if confirmed nephrite, depending on color, translucency, quality, and size.

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 during alteration, while nephrite forms through metamorphism and metasomatism of magnesium-rich rocks. Exact age and locality cannot be determined from the image.

Uses & applications

Used as a tumbled ornamental stone, carving material, and occasionally jewelry; nephrite-quality material has substantially greater value than ordinary serpentine.

Geological facts

“Greenstone” is a trade term covering several green rocks, including serpentine, nephrite, and chlorite-rich stones. A hardness or specific-gravity test is needed for reliable identification.

Field identification & locations

Commonly found in altered ultramafic terrains, including California, New Zealand, British Columbia, Russia, and China. Field clues include green mottling, moderate-to-heavy weight, and a smooth waxy polish; it may scratch glass if nephrite but not if serpentine.