metamorphic
Serpentinite
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
Hardness: 2.5 to 5 on Mohs scale; Color: Mottled green, black, or yellowish; Luster: Greasy, waxy, or silky; Crystal structure: Monoclinic; Cleavage: Poor; Specific gravity: 2.5-2.6.
- Hardness
- 2
- Color
- Mottled green, black, or yellowish
- Luster
- Greasy, waxy, or silky
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Physical properties
Hardness: 2.5 to 5 on Mohs scale; Color: Mottled green, black, or yellowish; Luster: Greasy, waxy, or silky; Crystal structure: Monoclinic; Cleavage: Poor; Specific gravity: 2.5-2.6.
Formation & geological history
Formed by the low-temperature hydrothermal alteration (serpentinization) of ultramafic rocks from the Earth's mantle, typically at tectonic plate boundaries or subduction zones.
Uses & applications
Used as a decorative architectural stone, a source of magnesium, historically for asbestos, and occasionally in jewelry as California Jade.
Geological facts
Serpentinite is the official state rock of California. It often contains magnetite, making some specimens slightly magnetic, and can host rare minerals like chromite.
Field identification & locations
Identified by its 'snake-skin' appearance, waxy feel, and green color variations. Commonly found in ophiolite complexes and mountain belts like the Coast Ranges of California or the Appalachians.
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