metamorphic
Serpentine
Serpentine Group (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale); Color: Varying shades of green from pale lime to dark olive with black inclusions; Luster: Greasy, waxy, or silky; Structure: Monoclinic; Cleavage: Poor; Specific Gravity: 2.5–2.6.
- Hardness
- 3-6 (Mohs scale)
- Luster
- Greasy, waxy, or silky
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Physical properties
Hardness: 3-6 (Mohs scale); Color: Varying shades of green from pale lime to dark olive with black inclusions; Luster: Greasy, waxy, or silky; Structure: Monoclinic; Cleavage: Poor; Specific Gravity: 2.5–2.6.
Formation & geological history
Formed through serpentinization, the low-temperature hydrothermal metamorphic alteration of ultramafic rocks (like peridotite) from the Earth's mantle, primarily occurring at tectonic plate boundaries and seafloor spreading centers.
Uses & applications
Used ornamentally for carvings, jewelry (as 'New Jade' or 'Infinite Stone'), architectural stone (green marble), and historically as a source of asbestos in some varieties.
Geological facts
Serpentine is the official state rock of California. It is named for its resemblance to the skin of a snake. It often contains inclusions of Magnetite, which can make some specimens slightly magnetic.
Field identification & locations
Identify in the field by its characteristic 'serpentine' green mottling, slippery or soapy feel, and relatively low hardness compared to jade. Commonly found in ophiolite belts in California, Canada, Cornwall (UK), and the Himalayas.
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