metamorphic
Serpentinite
Serpentinite (Mg3Si2O5(OH)4)
Hardness: 3-6 Mohs. Color: Green, brownish-green, or blackish-green. Luster: Greasy, waxy, or silky. Structure: Fibrous or massive. Cleavage: Poor.
- Hardness
- 3-6 Mohs
- Color
- Green, brownish-green, or blackish-green
- Luster
- Greasy, waxy, or silky
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Physical properties
Hardness: 3-6 Mohs. Color: Green, brownish-green, or blackish-green. Luster: Greasy, waxy, or silky. Structure: Fibrous or massive. Cleavage: Poor.
Formation & geological history
Formed through the hydration of ultramafic rocks (like peridotite) from the Earth's mantle at low temperatures and high pressures, typically at tectonic plate boundaries/subduction zones.
Uses & applications
Used as decorative architectural stone (terrazzo), as a source of magnesium, historically for asbestos fiber, and for carving and jewelry.
Geological facts
It is the official State Rock of California. Large deposits are found in the Coast Ranges and Klamath Mountains. It often creates unique soil conditions that lead to rare endemic plant species.
Field identification & locations
Look for a dull to waxy luster and a distinctive greenish, mottled 'serpent-skin' appearance. It feels slightly greasy or soapy to the touch. It is often associated with fault zones.
