metamorphic

Weathered greenstone / serpentinite (probable)

Serpentinite, chiefly antigorite–lizardite Mg₃Si₂O₅(OH)₄; possibly altered mafic greenstone

AI-generated identification · may be incorrect

Rounded, dense, fine-grained stone with muted olive-green, brown, and gray mottling, waxy-to-dull luster, and abundant weathering cracks. Serpentinite is typically Mohs 2.5–4, has poor cleavage, a massive texture, and specific gravity around 2.5–2.6; the image alone cannot confirm the diagnosis.

Identified September 3, 2026More metamorphic →

Explore Weathered greenstone / serpentinite (probable) 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: Weathered greenstone / serpentinite (probable)
Scientific name: Serpentinite, chiefly antigorite–lizardite Mg₃Si₂O₅(OH)₄; possibly altered mafic greenstone
Category: metamorphic
Identified: September 3, 2026
Method: Standard

AI Estimated Value

$5–$30 as an unverified common cobble; approximately $30–$150 if confirmed attractive serpentine or a documented locality specimen.

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

Usually forms when ultramafic mantle rocks hydrate during metamorphism, commonly in ancient subduction zones and ophiolites; ages vary widely from Precambrian to Recent tectonic settings. Its smooth shape likely reflects stream or beach transport and weathering.

Uses & applications

Used as decorative stone, carving material, aggregate, and occasionally ornamental lapidary material; attractive polished pieces may be sold as serpentine, though this specimen appears mainly collector-grade.

Geological facts

Serpentinite can contain magnetite and trace chrysotile asbestos, so avoid cutting, drilling, or generating dust until tested. A small dark green projecting area may be a separate mineral vein or inclusion.

Field identification & locations

Common in California, Vermont, Italy, New Zealand, and ophiolite belts worldwide. Check for a waxy feel, relatively low hardness, green streak or powder, and possible magnetism; acid reaction should be absent or weak. Definitive identification requires hardness, specific-gravity, and mineralogical testing.