metamorphic

Serpentine-rich pebble

Serpentinite; chiefly serpentine-group minerals (chrysotile, lizardite, antigorite), commonly with magnetite and minor olivine/pyroxene

AI-generated identification · may be incorrect

Typically pale green to yellow-green with mottled or waxy appearance; Mohs hardness about 2.5–4, vitreous to greasy luster, generally massive rather than visibly crystalline, and no consistent cleavage. The rounded form indicates natural abrasion or tumbling; the photograph alone cannot confirm the identification.

Identified August 9, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic rocks such as peridotite undergo low-temperature hydration and metamorphism, commonly in oceanic crust and tectonic mélange zones. Serpentinization is mainly Mesozoic to Cenozoic in exposed examples, though rocks of many ages occur.

Uses & applications

Used as decorative stone, carvings, countertops, and historically as a low-grade ornamental “marble”; some varieties are collected. Fibrous chrysotile-bearing material should not be cut or abraded because its dust can be hazardous.

Geological facts

Green color and waxy texture are characteristic, but similar-looking materials include chlorite-rich rocks, weathered basalt, and slag. A streak, hardness, magnetism, and specific-gravity test would improve identification.

Field identification & locations

Common in ophiolites and mountain belts, including California, Italy, New Zealand, and the Appalachians. Look for greasy green surfaces, black magnetite specks, relatively low hardness, and occasional weak magnetism.