metamorphic
Serpentine
Serpentinite (group of hydrous magnesium iron phyllosilicate minerals)
Hardness: 3-6 (Mohs scale), Color: shades of green to black, Luster: greasy, waxy, or silky, Crystal structure: Monoclinic, Cleavage: poor to perfect in one direction, Specific gravity: 2.2-2.9
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Physical properties
Hardness: 3-6 (Mohs scale), Color: shades of green to black, Luster: greasy, waxy, or silky, Crystal structure: Monoclinic, Cleavage: poor to perfect in one direction, Specific gravity: 2.2-2.9
Formation & geological history
Formed through serpentinization, a process where ultramafic rocks (like peridotite) from the Earth's mantle are chemically altered by heat and water at low temperatures. Common in tectonic plate boundaries.
Uses & applications
Used as decorative architectural stone, in jewelry (often as a jade simulant), and historically for heat-resistant laboratory surfaces and asbestos production before health risks were known.
Geological facts
The name comes from the Latin 'serpentinus', meaning 'serpent-like', due to its mottled green appearance resembling snakeskin. It is the official state rock of California.
Field identification & locations
Identify in the field by its characteristic 'greasy' feel and mottled green coloring. Frequently found in ophiolite complexes and metamorphic belts. Collectors look for translucent 'precocious' varieties.
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