metamorphic

Tumbled greenstone/serpentinite pebble

Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄; identification is visual and uncertain

AI-generated identification · may be incorrect

Dark olive-green, rounded and polished, with a dull to waxy luster and fine-grained texture. Typical hardness is 2.5–4 Mohs, no visible cleavage, and specific gravity about 2.5–2.6.

Identified September 10, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone/serpentinite pebble
Scientific name: Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄; identification is visual and uncertain
Category: metamorphic
Identified: September 10, 2026
Method: Standard

AI Estimated Value

$2–$15 for a common tumbled pebble; approximately $20–$100 for attractive larger or unusual polished specimens.

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

Dark olive-green, rounded and polished, with a dull to waxy luster and fine-grained texture. Typical hardness is 2.5–4 Mohs, no visible cleavage, and specific gravity about 2.5–2.6.

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite undergo low-temperature hydration and metamorphism, commonly in ancient oceanic crust and subduction zones. Serpentinite occurrences range from Precambrian to modern geological settings.

Uses & applications

Used as ornamental stone, carvings, beads, countertops, and landscaping material; attractive specimens are collected as polished pebbles. It is generally less durable than jade and should not be confused with true jadeite or nephrite.

Geological facts

The image shows a strongly rounded, likely tumbled specimen; exact identification cannot be confirmed without hardness, streak, density, or mineralogical testing. Some serpentinite contains chrysotile asbestos, so avoid cutting, drilling, or generating dust.

Field identification & locations

Common in ophiolites and alpine/subduction belts, including California, Italy, New Zealand, Canada, and Japan. A waxy feel, green mottling, low hardness, and possible white veining support serpentinite; jade is harder (about 6–7 Mohs).