metamorphic
Polished serpentinite pebble
Serpentinite; primarily serpentine-group minerals (Mg3Si2O5(OH)4), with possible magnetite and talc
AI-generated identification · may be incorrectHardness about 2.5–4 Mohs; olive-green to yellow-green, waxy/greasy luster, fine-grained massive texture, and irregular fracture rather than visible cleavage. The rounded, smooth surface indicates water polishing or deliberate tumbling.
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Physical properties
Hardness about 2.5–4 Mohs; olive-green to yellow-green, waxy/greasy luster, fine-grained massive texture, and irregular fracture rather than visible cleavage. The rounded, smooth surface indicates water polishing or deliberate tumbling.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite are hydrated during hydrothermal alteration, commonly along tectonic plate boundaries and ophiolites. Serpentinite can range from Paleozoic to modern tectonic settings.
Uses & applications
Used as a decorative stone, carving material, aggregate, and architectural stone; attractive pieces are collected but are generally inexpensive.
Geological facts
The yellow-green color and dark veining are characteristic of serpentine minerals, though exact identification requires testing. Some serpentinite contains chrysotile asbestos, so avoid cutting, sanding, or generating dust.
Field identification & locations
Common in California, Oregon, Washington, Italy, New Zealand, and other ophiolite belts; it is softer than quartz and may show a soapy feel and pale green streak. The image supports serpentinite, but a definitive identification would require hardness, streak, and mineralogical tests.
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