metamorphic
Serpentinite
Serpentinite ((Mg, Fe)3Si2O5(OH)4)
Hardness: 3-6 on Mohs scale; Color: Dark green to black, often with mottled light green patches; Luster: Waxy, greasy, or silky; Structure: Massive or fibrous; Specific Gravity: 2.5-2.6
- Hardness
- 3-6 on Mohs scale
- Color
- Dark green to black, often with mottled light green patches
- Luster
- Waxy, greasy, or silky
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Physical properties
Hardness: 3-6 on Mohs scale; Color: Dark green to black, often with mottled light green patches; Luster: Waxy, greasy, or silky; Structure: Massive or fibrous; Specific Gravity: 2.5-2.6
Formation & geological history
Formed by the hydrothermal metamorphism of ultramafic rocks (peridotite) from the Earth's mantle at low temperatures. Common at tectonic plate boundaries and ophiolite complexes.
Uses & applications
Used as decorative stone in architecture, as a source of magnesium, and historically as a source of asbestos. Used in carvings and jewelry (often called 'New Zealand Jade' or 'Bowenite').
Geological facts
Serpentinite is the official state rock of California. It often creates poor soil conditions that host unique, rare plant species because of its high magnesium and low calcium content.
Field identification & locations
Identify by its typically green color and 'snake-skin' pattern. It often feels slightly greasy or soapy to the touch. Found in mountain ranges where ancient seafloor was uplifted.
