metamorphic
Serpentine
Serpentine Group (primarily Antigorite or Lizardite), Mg3Si2O5(OH)4
Hardness: 3–6 on Mohs scale; Color: typically green to yellow-green with mottled streaks; Luster: waxy, greasy, or silky; Crystal Structure: Monoclinic; Cleavage: perfect on {001}; Specific Gravity: 2.5–2.6.
- Hardness
- 3–6 on Mohs scale
- Color
- typically green to yellow-green with mottled streaks
- Luster
- waxy, greasy, or silky
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Physical properties
Hardness: 3–6 on Mohs scale; Color: typically green to yellow-green with mottled streaks; Luster: waxy, greasy, or silky; Crystal Structure: Monoclinic; Cleavage: perfect on {001}; Specific Gravity: 2.5–2.6.
Formation & geological history
Formed through serpentinization, which occurs at low temperatures and high pressures where ultramafic igneous rocks (like peridotite) are hydrated in subduction zones. Common in ophiolite complexes.
Uses & applications
Used as a decorative architectural stone (California's state rock), in carvings, as a source for magnesium, and historically as a source for asbestos (Chrysotile variety).
Geological facts
The name comes from its resemblance to the skin of a serpent, often featuring mottled patches and a waxy texture. It is a key indicator of ancient tectonic plate boundaries.
Field identification & locations
Identify in the field by its distinctive 'greasy' or slippery feel, green mottled appearance, and susceptibility to being scratched by a steel knife (unlike nephrite jade). Commonly found in California, Canada, and the Alps.
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