metamorphic
Serpentine
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)3(Si,Al,Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale), Color: Dark green to yellowish-green with mottled patterns, Luster: Waxy to greasy, Crystal structure: Monoclinic or Orthorhombic (often fibrous or platy), Specific Gravity: 2.2-2.9
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Physical properties
Hardness: 3-6 (Mohs scale), Color: Dark green to yellowish-green with mottled patterns, Luster: Waxy to greasy, Crystal structure: Monoclinic or Orthorhombic (often fibrous or platy), Specific Gravity: 2.2-2.9
Formation & geological history
Formed primarily by the hydrothermal alteration (serpentinization) of mafic and ultramafic rocks like peridotite or pyroxenite, often at tectonic plate boundaries/subduction zones.
Uses & applications
Used for carvings, ornamental stone, jewelry (sometimes sold as 'New Jade'), and historically as a source for asbestos.
Geological facts
Serpentinite is the state rock of California; it is known for producing 'serpentine soils' which are rich in magnesium but toxic to many plants, leading to unique, adapted ecosystems.
Field identification & locations
Identifiable by its characteristic greasy feel, dark green mottled color resembling snake skin, and relative softness compared to nephrite jade. Common in ophiolite belts globally.
