metamorphic
Serpentinite
Serpentinite (Hydrated Magnesium Silicate Mg3Si2O5(OH)4)
Hardness: 3-6 Mohs. Color: dark green to black with mottled light green patches. Luster: waxy, greasy, or silky. Crystal structure: Monoclinic, often fibrous or massive. Cleavage: poor/basal. Specific Gravity: 2.5-2.6.
- Hardness
- 3-6 Mohs
- Color
- dark green to black with mottled light green patches
- Luster
- waxy, greasy, or silky
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Physical properties
Hardness: 3-6 Mohs. Color: dark green to black with mottled light green patches. Luster: waxy, greasy, or silky. Crystal structure: Monoclinic, often fibrous or massive. Cleavage: poor/basal. Specific Gravity: 2.5-2.6.
Formation & geological history
Formed through serpentinization, a low-temperature metamorphic process where ultramafic rocks (peridotite) from the Earth's mantle are hydrated by hydrothermal fluids at tectonic boundaries.
Uses & applications
Used as an ornamental stone in architecture, a source of magnesium, and historically as a source of asbestos. High-quality varieties like bowenite are used in jewelry as 'New Jade'.
Geological facts
Serpentinite is the official state rock of California. It often creates 'serpentine barrens' where the unique soil chemistry limits plant growth to specialized endemic species.
Field identification & locations
Identify by its characteristic 'snake-skin' appearance, waxy feel, and various shades of green. Commonly found in ophiolite complexes and subduction zones in places like California, Vermont, and the Alps.
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