metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale), Color: Dark green to blackish green with waxy or silky luster, Crystal structure: Monoclinic, Cleavage: Poor, Specific gravity: 2.2-2.9. It often has a soapy or greasy feel.
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Physical properties
Hardness: 3-6 (Mohs scale), Color: Dark green to blackish green with waxy or silky luster, Crystal structure: Monoclinic, Cleavage: Poor, Specific gravity: 2.2-2.9. It often has a soapy or greasy feel.
Formation & geological history
Formed through serpentinization, a process where ultramafic rocks from the Earth's mantle are chemically altered by hydrothermal fluids at relatively low temperatures and high pressures, often at tectonic plate boundaries.
Uses & applications
Used as a decorative architectural stone (Verde Antique), for carvings, as a source of asbestos in the past, and sometimes as a minor source of nickel or magnesium.
Geological facts
Serpentinite is the state rock of California. It is often associated with unique ecosystems because the soil it produces is high in magnesium and heavy metals but low in essential nutrients like calcium.
Field identification & locations
Identify in the field by its characteristic 'serpentine' green color, waxy luster, and smooth, slick surfaces (slickensides). Commonly found in mountain belts and ophiolite complexes.
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