metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 3-6 Mohs. Color: Greenish-yellow to dark green with brownish weathering. Luster: Greasy, waxy, or dull. Crystal Structure: Monoclinic (microcrystalline). Texture: Often slickensided or fibrous.
- Hardness
- 3-6 Mohs
- Color
- Greenish-yellow to dark green with brownish weathering
- Luster
- Greasy, waxy, or dull
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Physical properties
Hardness: 3-6 Mohs. Color: Greenish-yellow to dark green with brownish weathering. Luster: Greasy, waxy, or dull. Crystal Structure: Monoclinic (microcrystalline). Texture: Often slickensided or fibrous.
Formation & geological history
Formed through the hydration of ultramafic rocks (like peridotite) from the Earth's mantle during a process called serpentinization, typically at tectonic plate boundaries/subduction zones.
Uses & applications
Used as decorative architectural stone, source of asbestos (historically), and as a magnesium ore. Some varieties are used in jewelry as 'Jade' substitutes.
Geological facts
Serpentinite is the official state rock of California. The serpentinization process is exothermic and produces hydrogen gas, which can support microbial life in extreme environments.
Field identification & locations
Identify by its waxy look, greenish hue, and 'slick' feel when touched. Commonly found in ophiolite complexes where oceanic crust has been thrust onto continental crust.
