metamorphic
Tumbled serpentine
Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; commonly Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectTypically olive-green to blue-green with mottled dark veining, waxy to greasy luster, and opaque appearance; Mohs hardness 2.5–4, often with smooth tumbled surfaces and poor cleavage. The pictured specimen is consistent with serpentine, though exact identification requires testing.
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Physical properties
Typically olive-green to blue-green with mottled dark veining, waxy to greasy luster, and opaque appearance; Mohs hardness 2.5–4, often with smooth tumbled surfaces and poor cleavage. The pictured specimen is consistent with serpentine, though exact identification requires testing.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly in oceanic crust and subduction-zone mélanges. Serpentinization is generally Phanerozoic but occurs in rocks of many ages.
Uses & applications
Used as ornamental stone, carvings, beads, and decorative tile; some varieties have historical use as a jade substitute. Fibrous chrysotile varieties are asbestos-bearing and hazardous when dust is generated.
Geological facts
Its green color comes from iron and nickel-bearing alteration minerals; magnetite commonly forms during serpentinization. Serpentine is California’s state rock.
Field identification & locations
Look for a soft, waxy, mottled green stone that may scratch with a steel blade; it is commonly found in ultramafic terrains worldwide, including California, Italy, New Zealand, and Canada. Avoid sanding or breaking unknown specimens because some serpentine contains asbestos fibers.
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