metamorphic
Tumbled serpentinite (serpentine stone)
Serpentinite, dominated by serpentine-group minerals (lizardite, chrysotile, antigorite), commonly with magnetite and chromite
AI-generated identification · may be incorrectTypically dark green, black, brown, and yellow-banded, with a waxy to greasy luster and mottled veining; Mohs hardness 2.5–4, massive rather than visibly crystalline, with poor cleavage. The rounded, polished form is human-processed.
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Physical properties
Typically dark green, black, brown, and yellow-banded, with a waxy to greasy luster and mottled veining; Mohs hardness 2.5–4, massive rather than visibly crystalline, with poor cleavage. The rounded, polished form is human-processed.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along oceanic crust and tectonic plate boundaries; specimens may range from Paleozoic to recent geological settings.
Uses & applications
Used as ornamental stone, carvings, cabochons, beads, and tumbled specimens; massive serpentinite has limited architectural and decorative use. Fibrous chrysotile-bearing material should not be cut or abraded because dust can be hazardous.
Geological facts
The coloration and slick appearance are characteristic of serpentine minerals, but exact identification requires hardness, streak, density, or laboratory testing. It is commonly confused with nephrite jade, which is generally tougher and harder.
Field identification & locations
Common in California, Italy, New Zealand, Canada, Russia, and parts of the Appalachian and Alpine belts. Value is usually based on polish, pattern, size, and absence of asbestos fibers.
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