metamorphic

Polished greenstone pebble (likely serpentine or chlorite-rich stone)

Serpentine-group minerals, commonly antigorite/lizardite; possible chlorite-rich metamorphic rock

AI-generated identification · may be incorrect

Dark green to black, mottled, with a waxy to subdued vitreous luster and rounded polished surface; likely Mohs 2.5–4, lacking visible cleavage. Exact identification requires hardness, streak, density, and mineralogical testing.

Identified September 1, 2026More metamorphic →

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At a glance

Common name: Polished greenstone pebble (likely serpentine or chlorite-rich stone)
Scientific name: Serpentine-group minerals, commonly antigorite/lizardite; possible chlorite-rich metamorphic rock
Category: metamorphic
Identified: September 1, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a small common polished pebble; approximately $10–$50 if confirmed as attractive, high-quality ornamental serpentine or a rarer greenstone.

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

Typically formed by low- to moderate-temperature metamorphic hydration of ultramafic rocks, especially mantle-derived peridotite; deposits range from ancient Precambrian belts to younger ophiolites. The specimen appears human-polished or naturally water-rounded.

Uses & applications

Used as ornamental stone, carvings, beads, cabochons, and small collectible pebbles; massive serpentine has also been used decoratively in architecture. This small piece has little commercial value unless unusually attractive or analytically confirmed as a rarer greenstone.

Geological facts

Serpentine can resemble jade, but it is generally softer and less dense; some varieties contain magnetite, producing dark specks or weak magnetism. The image alone cannot distinguish serpentine from chlorite, nephrite, or other dark green rocks.

Field identification & locations

Look for a greasy/waxy green surface, low hardness, and occasional black magnetite grains; a steel nail may scratch it, while jade generally resists scratching. Common sources include California, New Zealand, Italy, Canada, and ophiolite belts worldwide.