metamorphic
Greenstone pebble (likely serpentinite)
Serpentinite, composed mainly of serpentine-group minerals
AI-generated identification · may be incorrectSmall, rounded, muted green-gray specimen with a smooth, possibly tumbled surface and subdued luster. Serpentine minerals are typically Mohs 2.5–5, with a fine-grained texture and no obvious crystal faces; composition cannot be confirmed from the image alone.
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Physical properties
Small, rounded, muted green-gray specimen with a smooth, possibly tumbled surface and subdued luster. Serpentine minerals are typically Mohs 2.5–5, with a fine-grained texture and no obvious crystal faces; composition cannot be confirmed from the image alone.
Formation & geological history
Serpentinite forms when water chemically alters ultramafic rocks, commonly in oceanic crust and subduction zones. The specimen’s geological age and exact formation history cannot be determined visually.
Uses & applications
Used as decorative stone, carvings, and lapidary material; attractive pieces may be polished for jewelry or display.
Geological facts
“Greenstone” is a broad descriptive term for green rocks, and this pebble could instead be another fine-grained green rock or mineral.
Field identification & locations
The rounded shape suggests river or beach transport, or tumbling by a person. Field identification requires tests such as hardness, streak, and close examination of texture; serpentinite occurs in many ancient and modern mountain belts.
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