metamorphic

Rounded green-gray stone, likely serpentinite or altered basalt

Serpentinite (antigorite/lizardite-rich), possibly serpentinized ultramafic rock

AI-generated identification · may be incorrect

Typically dark green to gray-green, waxy to dull luster, fine-grained and massive; Mohs hardness about 2.5–4, with variable density and no obvious cleavage. The specimen is waterworn and may show mottled iron-oxide staining.

Identified September 5, 2026More metamorphic →

Explore Rounded green-gray stone, likely serpentinite or altered basalt in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Rounded green-gray stone, likely serpentinite or altered basalt
Scientific name: Serpentinite (antigorite/lizardite-rich), possibly serpentinized ultramafic rock
Category: metamorphic
Identified: September 5, 2026
Method: Standard

AI Estimated Value

About $1–$10 as an ordinary waterworn specimen; $10–$40 if unusually patterned, polished, or confirmed as attractive serpentinite.

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

Serpentinite forms when mantle peridotite is hydrated and metamorphosed by fluids, commonly along faults and oceanic crust boundaries; alteration ages range from Precambrian to modern tectonic settings. A basaltic alternative would be fine-grained volcanic rock altered by weathering.

Uses & applications

Commonly used as decorative stone, carvings, countertops, and landscaping aggregate; attractive pieces are collected, though this small rounded specimen has limited commercial value.

Geological facts

Serpentinite may contain magnetite and can weakly attract a magnet; some varieties contain chrysotile asbestos, so avoid cutting, drilling, or generating dust until tested.

Field identification & locations

Look for a green color, smooth/waxy surface, mottled pattern, and softness relative to quartz; a streak, hardness, density, and magnetism test would distinguish it from basalt or greenstone. Common in California, the Appalachians, New Zealand, Italy, and other ophiolite belts.