metamorphic
Polished serpentine (likely chrysotile-rich serpentinite)
Serpentinite; chiefly antigorite, lizardite, and/or chrysotile, Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectDark green to black mottling with a waxy-to-subvitreous luster; Mohs hardness about 2.5–4, commonly massive and opaque, with no obvious crystal cleavage. The rectangular form appears cut and polished.
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Physical properties
Dark green to black mottling with a waxy-to-subvitreous luster; Mohs hardness about 2.5–4, commonly massive and opaque, with no obvious crystal cleavage. The rectangular form appears cut and polished.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydrothermal alteration and hydration, commonly in oceanic crust and subduction zones. Serpentinization ranges from Precambrian to Recent geological ages.
Uses & applications
Used as ornamental stone, carvings, cabochons, and small polished specimens; massive serpentinite has limited architectural and landscaping use. Chrysotile-bearing material should not be cut or abraded because dust may be hazardous.
Geological facts
Often shows a characteristic green, black, or yellowish “snake-skin” pattern and may contain magnetite, chromite, or carbonate veins. It is softer and less durable than jade, despite occasional marketing as “serpentine jade.”
Field identification & locations
Identify by its low hardness, greasy or waxy feel, green-black mottling, and possible white veining; a steel point usually scratches it. Common localities include California, Italy, New Zealand, Canada, and Afghanistan.
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