metamorphic

Tumbled greenstone (likely serpentine or nephrite)

Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly nephrite, a fibrous amphibole aggregate

AI-generated identification · may be incorrect

Olive-green, rounded, and polished with a waxy to silky luster; hardness is typically 2.5–4 for serpentine and 6–6.5 for nephrite. The image is insufficient to determine cleavage, crystal structure, or specific gravity reliably.

Identified August 16, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentine or nephrite)
Scientific name: Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly nephrite, a fibrous amphibole aggregate
Category: metamorphic
Identified: August 16, 2026
Method: Standard

AI Estimated Value

About $2–$15 as a common tumbled serpentine; approximately $20–$100+ if confirmed 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 rocks undergo hydration and metamorphism, commonly in ophiolites and fault zones; nephrite forms by metamorphic alteration of magnesium-rich rocks. A precise geological age cannot be determined visually.

Uses & applications

Used as a carving and ornamental stone, beads, cabochons, and tumbled specimens; nephrite is also a valued jade material. Serpentine is used decoratively and occasionally as a low-grade building stone.

Geological facts

The smooth triangular shape and reflective surface indicate human tumbling or polishing. A scratch test, density measurement, and magnification are needed to distinguish serpentine from jade.

Field identification & locations

Common sources include California, Oregon, Canada, New Zealand, China, and Central Asia. Serpentine is generally softer and waxier; nephrite is notably tough, denser, and resists scratching by a steel file.