metamorphic
Serpentine (polished/tumbled)
Serpentinite; predominantly antigorite, lizardite, and/or chrysotile, commonly with magnetite
AI-generated identification · may be incorrectTypically olive-, yellow-, or dark-green with mottled fibrous veining and waxy to greasy luster; Mohs hardness 2.5–4, poor cleavage, and fine-grained massive texture. The rounded glossy surface indicates polishing or tumbling.
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Physical properties
Typically olive-, yellow-, or dark-green with mottled fibrous veining and waxy to greasy luster; Mohs hardness 2.5–4, poor cleavage, and fine-grained massive texture. The rounded glossy surface indicates polishing or tumbling.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and alteration during tectonic processes, especially along oceanic crust and subduction zones. Most examples formed in Precambrian to Cenozoic ophiolite belts; age depends on locality.
Uses & applications
Used as decorative stone, carvings, cabochons, beads, and architectural facing stone; historically used for ornaments and containers. Chrysotile-rich material can contain asbestos fibers and should not be cut or powdered without proper controls.
Geological facts
Serpentinite is named for its resemblance to snakeskin. Its green color commonly results from iron-bearing serpentine minerals, while black specks or streaks may be magnetite or chromite.
Field identification & locations
Identify by its soft, waxy feel, mottled green-black appearance, lack of visible quartz crystals, and ability to scratch relatively easily with a steel knife; exact identification requires testing because similar greenstones include nephrite and chlorite schist. Common in California, Italy, New Zealand, Canada, and ophiolite complexes worldwide.
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