metamorphic
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals: (Mg,Fe)3Si2O5(OH)4)
Hardness: 3-6 on Mohs scale; Color: Greenish-gray to dark green; Luster: Waxy, greasy, or silky; Texture: Fine-grained to fibrous; Cleavage: Often exhibits a scaly or foliate appearance.
- Hardness
- 3-6 on Mohs scale
- Color
- Greenish-gray to dark green
- Luster
- Waxy, greasy, or silky
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Physical properties
Hardness: 3-6 on Mohs scale; Color: Greenish-gray to dark green; Luster: Waxy, greasy, or silky; Texture: Fine-grained to fibrous; Cleavage: Often exhibits a scaly or foliate appearance.
Formation & geological history
Formed through the hydration and metamorphic transformation of ultramafic rocks (like peridotite) from the Earth's mantle, typically at tectonic plate boundaries (subduction zones) where water is introduced to high-pressure environments.
Uses & applications
Used as decorative architectural stone, in sculptures, as a source for asbestos in the past, and as a shielding material in nuclear reactors (due to high water content).
Geological facts
Serpentinite is the official state rock of California. It often creates unique soil conditions that lead to specialized local flora known as serpentine endemics.
Field identification & locations
Identify by its characteristic green color, soapy or waxy feel, and common association with 'slickensides' (polished, grooved surfaces from tectonic movement). Found in ophiolite belts globally.
