metamorphic

Serpentinite (likely antigorite-rich)

Serpentine-group rock; chiefly antigorite, lizardite, and/or chrysotile, approximately Mg3Si2O5(OH)4

AI-generated identification · may be incorrect

Dark green to black, mottled and waxy to greasy luster, with locally slick surfaces; typically Mohs 2.5–4, poor cleavage, and fine-grained to fibrous crystal structure. The image alone cannot confirm mineral identity; a streak, hardness, and acid test would help.

Identified September 9, 2026More metamorphic →

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At a glance

Common name: Serpentinite (likely antigorite-rich)
Scientific name: Serpentine-group rock; chiefly antigorite, lizardite, and/or chrysotile, approximately Mg3Si2O5(OH)4
Category: metamorphic
Identified: September 9, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$150 or more for attractive polished, patterned, or locality-labeled pieces.

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 rocks such as peridotite hydrate during low- to medium-temperature metamorphism, commonly along oceanic crust and tectonic fault zones. It can range from ancient Precambrian bodies to younger ophiolite complexes.

Uses & applications

Used as decorative stone, carvings, countertops, and historically as a source of asbestos-bearing material; chrysotile varieties require health precautions. Attractive specimens are collected as ornamental stone.

Geological facts

Field clues include green-black color, low hardness, waxy feel, and abundant slickensides; it may scratch with a knife and usually does not fizz with dilute hydrochloric acid. Common localities include California, Vermont, Italy, New Zealand, and ophiolite belts worldwide.

Field identification & locations

Likely identification rather than certainty because the specimen is unlabelled and weathered; alternatives include chlorite-rich metamorphic rock or greenstone. Avoid cutting or abrading it until asbestos content is excluded.