metamorphic
Serpentine
Serpentine-group minerals (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale), Color: shades of waxy green to black/yellow, Luster: greasy, waxy or silky, Crystal structure: Monoclinic, Cleavage: Poor to perfect, Specific Gravity: 2.5-2.6
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Physical properties
Hardness: 3-6 (Mohs scale), Color: shades of waxy green to black/yellow, Luster: greasy, waxy or silky, Crystal structure: Monoclinic, Cleavage: Poor to perfect, Specific Gravity: 2.5-2.6
Formation & geological history
Formed through the hydration and metamorphic transformation of ultramafic rocks (like peridotite) from the Earth's mantle, typically in subduction zones or seafloor spreading centers.
Uses & applications
Used for architectural stone (Verde Antique), decorative carvings, jewelry (cabochons), and historically as a source for asbestos (in the chrysotile variety).
Geological facts
Serpentine is the official state rock of California. It gets its name from its similarity to the texture and color of serpent skin. It often contains magnetite, which can make some specimens slightly magnetic.
Field identification & locations
Identify by its characteristic greasy feel, mottled green appearance, and relative softness (can often be scratched by a copper penny or steel knife). Commonly found in mountain belts and ophiolite complexes.
