metamorphic
Tumbled serpentine
Serpentinite; chiefly antigorite, lizardite, and/or chrysotile serpentine-group minerals
AI-generated identification · may be incorrectOlive-green to yellow-green, mottled and polished, with a waxy to resinous luster; Mohs hardness about 2.5–4, commonly massive with no visible crystal cleavage. The pictured pebble may also contain dark magnetite or lighter carbonate minerals.
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Physical properties
Olive-green to yellow-green, mottled and polished, with a waxy to resinous luster; Mohs hardness about 2.5–4, commonly massive with no visible crystal cleavage. The pictured pebble may also contain dark magnetite or lighter carbonate minerals.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and low-temperature metamorphism, commonly along tectonic plate boundaries and fault zones. Serpentinite ranges from Precambrian to modern geological ages.
Uses & applications
Used as ornamental stone, carvings, beads, cabochons, and decorative tile; historically used as a jade substitute. Fibrous chrysotile varieties have asbestos hazards and should not be cut, drilled, or powdered.
Geological facts
Its green color results from serpentine minerals and iron-bearing alteration products. Serpentinite is California’s state rock and commonly forms distinctive slickensided, green terrains.
Field identification & locations
Identify by its greasy or waxy feel, mottled green color, low hardness, and tendency to scratch with a steel knife; it is softer than true jade. Common localities include California, Italy, New Zealand, Canada, and the Ural Mountains.
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