metamorphic

Dark green-gray river-worn rock, likely serpentinite

Serpentinite (rock composed chiefly of serpentine-group minerals; identification is provisional from the photograph)

AI-generated identification · may be incorrect

Smooth, rounded, dark green to gray surface with a subdued, slightly waxy sheen. Serpentine minerals have Mohs hardness about 2.5–5.5 and a platy to fibrous structure; the specimen’s exact hardness and composition cannot be established visually.

Identified October 13, 2026More metamorphic →

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At a glance

Common name: Dark green-gray river-worn rock, likely serpentinite
Scientific name: Serpentinite (rock composed chiefly of serpentine-group minerals; identification is provisional from the photograph)
Category: metamorphic
Identified: October 13, 2026
Method: Standard

AI Estimated Value

Approximately $1–$20 for a common rounded specimen of this apparent size; distinctive polished or collectible pieces may sell for more.

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

Forms when magnesium-rich ultramafic rocks are altered by water, commonly along tectonic plate boundaries and in mountain belts. Serpentinization can occur at different geological ages; river transport likely rounded this specimen.

Uses & applications

Serpentinite is used as decorative and carving stone, landscaping material, and occasionally as a source of serpentine minerals; quality depends on composition and appearance.

Geological facts

Serpentinite is a rock rather than a single mineral and may contain several serpentine minerals, magnetite, and remnants of olivine or pyroxene.

Field identification & locations

Look for green color, smooth or waxy surfaces, and possible dark magnetite flecks; confirm with hardness, streak, and mineral testing. Found in ultramafic-rock belts worldwide; the photo alone cannot confirm the identification.