metamorphic

Tumbled river stones, likely serpentinite/greenstone and quartzite

Serpentinite or chlorite-rich greenstone; gray quartzite; brown altered metamorphic rock (visual identification uncertain)

AI-generated identification · may be incorrect

Smooth, rounded, machine-tumbled specimens with dull to subtly waxy luster. Likely hardness ranges from Mohs 3–4 for serpentinite/greenstone and 6.5–7 for quartzite; colors are olive green, gray, and tan, with no visible cleavage or crystals.

Identified September 14, 2026More metamorphic →

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At a glance

Common name: Tumbled river stones, likely serpentinite/greenstone and quartzite
Scientific name: Serpentinite or chlorite-rich greenstone; gray quartzite; brown altered metamorphic rock (visual identification uncertain)
Category: metamorphic
Identified: September 14, 2026
Method: Standard

AI Estimated Value

About $1–$10 each as ordinary tumbled stones; roughly $10–$30 for attractive, well-polished pieces, depending on confirmed material and provenance.

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

These are likely naturally weathered stream pebbles that were subsequently polished by tumbling; serpentinite forms by hydration of ultramafic mantle rocks, while quartzite forms by metamorphism of sandstone. Their precise geological ages and localities cannot be determined from the image.

Uses & applications

Commonly used for lapidary work, crafts, decorative gravel, and beginner stone collections; attractive pieces may be sold as worry stones or polished pebbles.

Geological facts

The large green pebble may be marketed commercially as serpentine, jade-like greenstone, or “new jade,” but appearance alone cannot distinguish these materials from jade or other green rocks.

Field identification & locations

Field identification requires hardness, streak, density, magnetism, and acid tests; quartzite scratches glass, whereas serpentinite usually does not. Common sources include river gravels and serpentinite belts worldwide.