metamorphic
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals like Antigorite, Lizardite, and Chrysotile)
Hardness: 3-6 (Mohs scale), Color: Varying shades of green from pale to blackish-green, Luster: Greasy, waxy, or silky, Crystal Structure: Monoclinic, Cleavage: Poor, Specific Gravity: 2.2-2.9
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Physical properties
Hardness: 3-6 (Mohs scale), Color: Varying shades of green from pale to blackish-green, Luster: Greasy, waxy, or silky, Crystal Structure: Monoclinic, Cleavage: Poor, Specific Gravity: 2.2-2.9
Formation & geological history
Formed through the hydration and metamorphic transformation of ultramafic rock (like peridotite) from the Earth's mantle. This process, called serpentinization, typically occurs at tectonic plate boundaries.
Uses & applications
Used as decorative stone, for carvings, as a source of magnesium, and historically as a source of asbestos. High-quality varieties like Williamsite are used in jewelry.
Geological facts
It is the official state rock of California. The name comes from the green color and scaly appearance, which resembles the skin of a serpent.
Field identification & locations
Identified by its distinctive soapy or greasy feel and mottled green color. Common in ophiolite complexes and along fault zones. Collectors look for translucent green specimens or those with interesting veins.
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