metamorphic
Serpentine
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale), Color: Mottled green, dark brown, or black, Luster: Waxy to greasy, Crystal structure: Monoclinic, Cleavage: Poor/perfect basal for some varieties, Specific Gravity: 2.5-2.8
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Physical properties
Hardness: 3-6 (Mohs scale), Color: Mottled green, dark brown, or black, Luster: Waxy to greasy, Crystal structure: Monoclinic, Cleavage: Poor/perfect basal for some varieties, Specific Gravity: 2.5-2.8
Formation & geological history
Formed through the hydration of ultramafic rocks (like peridotite) from the Earth’s mantle during low-temperature metamorphism (serpentinization) at tectonic plate boundaries.
Uses & applications
Used primarily in jewelry as cabochons or beads, ornamental carvings, decorative architecture, and historically as a source of asbestos or magnesium.
Geological facts
The name comes from the Latin 'serpentinus', meaning 'serpent rock,' because of its resemblance to the skin of a snake. It is the state rock of California.
Field identification & locations
Identify by its characteristic waxy luster, slippery/soapy feel when wet, and mottled green-to-black color. Commonly found in ophiolite complexes and mountain ranges.
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