metamorphic

Rounded greenstone pebble

Likely serpentinite or chlorite-rich metamorphic rock; exact identification requires testing

AI-generated identification · may be incorrect

Fine-grained, rounded, mottled olive-green and brown surface with dull to slightly waxy luster; likely Mohs hardness about 2.5–5.5, with no visible cleavage or crystals. The shape appears naturally water-worn.

Identified August 9, 2026More metamorphic →

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Physical properties

Formation & geological history

Probably formed by low- to moderate-temperature alteration or metamorphism of ultramafic rock, potentially during ancient oceanic or tectonic processes; age cannot be determined from the photograph. Its rounded form indicates later stream, beach, or glacial transport.

Uses & applications

Suitable as a curiosity, pocket stone, or lapidary material if it polishes well; serpentinite and related greenstones are also used decoratively and occasionally as dimension stone.

Geological facts

Green color commonly comes from serpentine, chlorite, epidote, or other iron- and magnesium-rich minerals. Serpentinite may contain trace chrysotile asbestos, so avoid cutting, grinding, or generating dust until identified.

Field identification & locations

Look for a distinctly green, mottled, dense stone with a waxy feel and possible dark veining; a streak, hardness, magnetic, and specific-gravity test would help distinguish serpentinite from green basalt or altered granite. Common in tectonically active mountain belts and former oceanic crust.