metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 2.5-5; Color: Dark green to black with waxy or greasy luster; Crystal Structure: Monoclinic; Cleavage: Poor; Specific Gravity: 2.5-2.6. Often displays polished-looking 'slickensides'.
- Hardness
- 2
- Color
- Dark green to black with waxy or greasy luster
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Physical properties
Hardness: 2.5-5; Color: Dark green to black with waxy or greasy luster; Crystal Structure: Monoclinic; Cleavage: Poor; Specific Gravity: 2.5-2.6. Often displays polished-looking 'slickensides'.
Formation & geological history
Formed by the hydration of ultramafic rocks from the Earth's mantle (serpentinization) at low temperatures and high pressures in subduction zones.
Uses & applications
Used as decorative architectural stone, a source of magnesium, and historically as a source of asbestos. High-quality varieties like 'Bowenite' are used in jewelry.
Geological facts
Serpentinite is the official state rock of California. It often creates unique soil chemistry that supports rare, endemic plant species that can tolerate high magnesium and heavy metals.
Field identification & locations
Identify by its waxy 'snake-skin' appearance and mottled green color. Commonly found in ophiolite complexes and along major fault lines where mantle rocks have been uplifted.
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