metamorphic
Tumbled/rounded serpentine-rich stone
Serpentinite; chiefly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile, with possible magnesite and magnetite
AI-generated identification · may be incorrectPale yellow-green, mottled, waxy to dull luster, massive and fine-grained; Mohs hardness typically 2.5–4, with no visible cleavage and specific gravity about 2.5–2.6. The rounded, worn shape indicates natural abrasion or human tumbling.
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Physical properties
Pale yellow-green, mottled, waxy to dull luster, massive and fine-grained; Mohs hardness typically 2.5–4, with no visible cleavage and specific gravity about 2.5–2.6. The rounded, worn shape indicates natural abrasion or human tumbling.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydrothermal metamorphism and hydration, commonly along ancient oceanic crust and tectonic fault zones. Individual specimens may range from ancient Precambrian to younger Mesozoic/Cenozoic settings.
Uses & applications
Used as decorative stone, carvings, beads, cabochons, and occasionally architectural stone; low-grade material has limited industrial value. Chrysotile-bearing varieties should not be cut, drilled, or powdered because asbestos fibers may be released.
Geological facts
Serpentinite commonly shows green, yellow, black, or brown coloration from iron and alteration minerals. Its slippery, waxy feel and mottled appearance are characteristic, but laboratory or chemical testing may be needed for confident identification.
Field identification & locations
Common in California, Italy, New Zealand, Canada, and ophiolite belts worldwide. Check for a waxy texture, low hardness, pale green streak or powder, and reaction to dilute acid if carbonate veins are present; the pictured specimen is a moderate-confidence identification.
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