metamorphic

Serpentinite

Serpentinite; chiefly serpentine-group minerals (lizardite, chrysotile, antigorite), commonly with magnetite and minor chromite

AI-generated identification · may be incorrect

Dark olive-green, mottled and waxy to greasy luster; typically massive with no visible crystals. Mohs hardness is about 2.5–4, with variable density around 2.5–2.6; the polished surface may show black magnetite specks.

Identified September 21, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite are hydrated during metamorphism, commonly in oceanic crust and subduction zones. Individual samples may range from Paleozoic to modern tectonic settings.

Uses & applications

Used as decorative stone, carvings, cabochons, and occasionally countertops; historically used for architectural stone. Chrysotile-bearing material should not be cut or abraded because inhaled fibers are hazardous.

Geological facts

The green color comes from serpentine minerals and iron; magnetite commonly forms during alteration. Some serpentinites are mistaken for jade, but they are generally softer and less tough.

Field identification & locations

Identify by its mottled green-black color, waxy polish, low hardness, and possible magnetism; a steel knife may scratch it. Common in California, Italy, New Zealand, Canada, and ophiolite belts worldwide.