metamorphic

Serpentinite

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, chrysotile)

AI-generated identification · may be incorrect

Typically dark green to mottled green, waxy to dull luster, fine-grained and massive; Mohs hardness about 2.5–4, with poor or no visible cleavage and specific gravity around 2.5–2.6. The specimen’s green, mottled appearance is consistent with serpentinite, though a photo cannot confirm composition.

Identified September 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite are hydrated during low-temperature metamorphism, commonly along oceanic crust and subduction zones. Individual pieces may range from ancient Precambrian to younger Phanerozoic exposures.

Uses & applications

Used as decorative and architectural stone, carving material, and a source rock associated with chromite, magnetite, and sometimes asbestos minerals. Small common specimens generally have limited commercial value.

Geological facts

Serpentinite often contains magnetite, producing a weak magnetic response, and may show slick, polished-looking surfaces. Chrysotile-bearing material can release hazardous fibers if cut, crushed, or abraded.

Field identification & locations

Look for mottled green color, waxy texture, relatively low hardness, and dense massive structure; a steel nail may scratch it. Common localities include California, Italy, Greece, New Zealand, and the Appalachian Mountains.