metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 3-6 Mohs (varies); Color: Mottled green, dark green, or blackish-green; Luster: Waxy to greasy or silky; Texture: Smooth, sometimes fibrous or massive; Specific Gravity: 2.5-2.6
- Hardness
- 3-6 Mohs (varies)
- Color
- Mottled green, dark green, or blackish-green
- Luster
- Waxy to greasy or silky
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Physical properties
Hardness: 3-6 Mohs (varies); Color: Mottled green, dark green, or blackish-green; Luster: Waxy to greasy or silky; Texture: Smooth, sometimes fibrous or massive; Specific Gravity: 2.5-2.6
Formation & geological history
Formed through the hydration and metamorphic transformation of ultramafic rock (peridotite) from the Earth's mantle, a process called serpentinization, typically at tectonic plate boundaries.
Uses & applications
Used as a decorative architectural stone, source of magnesium, historical source of asbestos (in some varieties), and for jewelry carving.
Geological facts
Serpentinite is the official state rock of California. It is unique for forming soils that are poor in essential nutrients but high in heavy metals, leading to specialized plant evolution.
Field identification & locations
Identify by its characteristic 'serpent-like' green mottled appearance and waxy feel. Commonly found in ophiolite complexes, the Coast Ranges of California, and the Appalachian Mountains.
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