metamorphic
Tumbled greenish-gray stone, likely serpentinite
Serpentinite; chiefly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile
AI-generated identification · may be incorrectMohs hardness 2.5–5.5; dull to waxy luster; green-gray color with mottled pale flecks; typically massive and noncrystalline, with no obvious cleavage. The rounded shape indicates tumbling or water wear.
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Physical properties
Mohs hardness 2.5–5.5; dull to waxy luster; green-gray color with mottled pale flecks; typically massive and noncrystalline, with no obvious cleavage. The rounded shape indicates tumbling or water wear.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly in oceanic crust and subduction-zone mélanges. Individual pieces may range from ancient Precambrian to younger tectonic settings.
Uses & applications
Used as a decorative and carving stone, ornamental aggregate, and occasionally dimension stone; attractive pieces are collected, though chrysotile-bearing material should not be cut or powdered.
Geological facts
Serpentinite is California’s former state rock and commonly records tectonic movement along faults. Its green color comes from iron- and magnesium-rich serpentine minerals.
Field identification & locations
Identify by its smooth waxy feel, low-to-moderate hardness, green mottling, and unusually light density; a streak, hardness, and magnetic test can help distinguish it from jade or chlorite-rich rocks. Common in serpentinite belts worldwide, including California, Italy, New Zealand, and Canada.
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