metamorphic
Serpentine
Antigorite, Lizardite, or Chrysotile (Mg,Fe)3Si2O5(OH)4
Hardness: 3-6 (Mohs scale), Color: Varying shades of green (oil-green to yellowish-green), Luster: Waxy, greasy or silky, Crystal structure: Monoclinic, Cleavage: Basal (perfect on {001}), Specific gravity: 2.2-2.9
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Physical properties
Hardness: 3-6 (Mohs scale), Color: Varying shades of green (oil-green to yellowish-green), Luster: Waxy, greasy or silky, Crystal structure: Monoclinic, Cleavage: Basal (perfect on {001}), Specific gravity: 2.2-2.9
Formation & geological history
Formed through the hydrothermal alteration of ultramafic rocks (like peridotite or pyroxenite) at low temperatures in the presence of water, a process known as serpentinization. Often found in ophiolite complexes and subduction zones.
Uses & applications
Used as an architectural stone (terrazzo tiles), a source of magnesium, ornamental carvings, and low-cost gemstones. Fibrous varieties (Chrysotile) were historically used for fire-resistant asbestos.
Geological facts
Serpentine is the official state rock of California. It often creates 'serpentine barrens,' unique ecosystems with poor soil quality that only specific, rare plants can survive in.
Field identification & locations
Identify by its characteristic greasy feel, waxy appearance, and varying green mottled patterns (resembling snakeskin). Commonly found in Vermont, California, the Alps, and Greece. Collectors should look for chatoyant (cat's eye) varieties or translucent 'precious serpentine'.
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