metamorphic
Serpentine
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
Hardness: 3-6 (Mohs scale); Color: Shades of green, yellowish, or blackish green; Luster: Waxy, greasy, or silky; Crystal structure: Monoclinic; Cleavage: Good in one direction; Specific gravity: 2.2-2.9
- Hardness
- 3-6 (Mohs scale)
- Color
- Shades of green, yellowish, or blackish green
- Luster
- Waxy, greasy, or silky
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Physical properties
Hardness: 3-6 (Mohs scale); Color: Shades of green, yellowish, or blackish green; Luster: Waxy, greasy, or silky; Crystal structure: Monoclinic; Cleavage: Good in one direction; Specific gravity: 2.2-2.9
Formation & geological history
Formed through serpentinization, a metamorphic process where ultramafic rocks (low in silica, high in magnesium/iron) are hydrated at low temperatures. Common in oceanic crust and subduction zones.
Uses & applications
Used as decorative stone, in jewelry (cabochons), as source for magnesium, and historically as fire-resistant material (asbestos varieties). Polished spheres are popular for meditation and home decor.
Geological facts
The name comes from 'serpentinus' (Latin for snake-like) due to its mottled green appearance that resembles snake skin. It is the state rock of California.
Field identification & locations
Identify in the field by its distinctive 'greasy' feel, green color with mottled veins, and relative softness (can often be scratched by a copper coin or knife). Primarily found in tectonic plate boundaries.
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