metamorphic

Serpentine-rich greenstone (probable serpentinized rock)

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite, carbonate, or chlorite

AI-generated identification · may be incorrect

Green to gray-green, mottled and fine-grained with a waxy to dull luster; typically hardness 2.5–4, no obvious cleavage, and specific gravity about 2.5–2.6. The rounded shape appears tumbled or naturally water-worn.

Identified September 12, 2026More metamorphic →

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At a glance

Common name: Serpentine-rich greenstone (probable serpentinized rock)
Scientific name: Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite, carbonate, or chlorite
Category: metamorphic
Identified: September 12, 2026
Method: Standard

AI Estimated Value

Typically $5–$30 for a small common tumbled specimen; attractive polished or carved pieces may sell for $30–$150.

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 ultramafic mantle rocks such as peridotite are altered by hot, water-rich fluids during tectonic activity, commonly in ophiolites and subduction zones. Exact geological age cannot be determined from the photograph.

Uses & applications

Used as decorative stone, carvings, architectural facing, and occasionally jewelry; softer varieties polish readily but may contain asbestos-form serpentine, so avoid cutting or generating dust until tested.

Geological facts

The pale web-like patches may be carbonate, quartz, or altered minerals, while the dark green matrix is consistent with serpentine. Visual identification is provisional because lighting and surface treatment obscure diagnostic details.

Field identification & locations

Common in California, the Italian Alps, New Zealand, Canada, and ophiolite belts worldwide. Field checks include a waxy feel, low hardness, green streak or powder, and possible magnetism; definitive identification requires hardness, streak, magnetism, or laboratory testing.