metamorphic

Serpentinite

Serpentine-group minerals, chiefly antigorite, lizardite, and chrysotile; approximate formula Mg3Si2O5(OH)4

AI-generated identification · may be incorrect

Typically dark green to greenish-black, waxy or greasy luster, fine-grained and massive; Mohs hardness 2.5–4, with commonly poor cleavage and specific gravity around 2.5–2.6. This specimen appears polished or naturally smoothed, so its texture is less diagnostic.

Identified September 10, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic rocks such as peridotite or dunite undergo low-temperature hydration (serpentinization), commonly along oceanic crust and tectonic plate boundaries. Most examples range from ancient Precambrian to modern tectonic settings.

Uses & applications

Used as decorative and carving stone, ornamental tile, and occasionally as a source of magnesium; historically used for sculpture and architectural facing. Chrysotile-rich material may contain asbestos and should not be cut, drilled, or powdered without testing and controls.

Geological facts

Often associated with chromite, magnetite, talc, and asbestos minerals, and can host unusual nickel and platinum-group mineralization.

Field identification & locations

Identify it by its green color, low hardness, waxy feel, dense massive texture, and association with ultramafic rocks; common localities include California, Italy, New Zealand, Canada, and the Appalachian region. Estimated value: $5–$30 for a common hand specimen, or $30–$150 if unusually attractive or polished.