metamorphic

Serpentine (serpentinite)

Serpentine-group minerals: mainly antigorite, lizardite, and/or chrysotile; commonly with magnetite and carbonate

AI-generated identification · may be incorrect

Hardness about 2.5–4 Mohs; dark green to yellow-green mottled color, waxy to greasy luster, massive structure, and poor or absent cleavage. The rounded surface appears naturally weathered or tumbled; exact identification needs testing.

Identified September 10, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic rocks such as peridotite undergo hydrothermal metamorphism and hydration, commonly along oceanic crust and tectonic faults. Individual specimens may be Paleozoic to younger, depending on the host terrane.

Uses & applications

Used as decorative stone, carvings, cabochons, and historically for architectural surfaces; some serpentinite is quarried as a dimension stone. Chrysotile-bearing material should not be cut, drilled, or crushed because asbestos fibers may be hazardous.

Geological facts

Its green coloration comes from iron- and magnesium-rich serpentine minerals. A useful field clue is its relatively low hardness: a steel knife may scratch it, while quartz will not.

Field identification & locations

Common in ophiolites and ultramafic belts, including California, Italy, New Zealand, and Canada. Confirm with a hardness test, streak, specific gravity, and ideally thin-section or Raman/XRD analysis; similar-looking rocks include nephrite, chlorite schist, and greenstone.