metamorphic
Serpentine
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
Hardness: 3-6 Mohs. Color: mottled green to black. Luster: waxy, greasy, or silky. Structure: monoclinic/triclinic. Cleavage: poor. Specific gravity: 2.2-2.9.
- Hardness
- 3-6 Mohs
- Color
- mottled green to black
- Luster
- waxy, greasy, or silky
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Physical properties
Hardness: 3-6 Mohs. Color: mottled green to black. Luster: waxy, greasy, or silky. Structure: monoclinic/triclinic. Cleavage: poor. Specific gravity: 2.2-2.9.
Formation & geological history
Formed by the serpentinization (hydration and metamorphic transformation) of ultramafic rocks from the Earth's mantle, such as peridotite, at relatively low temperatures and high pressures in the presence of water.
Uses & applications
Used for carvings, decorative architectural stone, jewelry (as 'New Jade'), and historically as a source of asbestos and magnesium.
Geological facts
Serpentine is the state rock of California; it is named for its resemblance to the skin of a serpent. Many varieties contain fibrous minerals like chrysotile.
Field identification & locations
Identified by its distinctive mottled green color, waxy feel, and softness compared to nephrite jade. Often found along fault zones and tectonic plate boundaries.
