metamorphic

Likely serpentinite (greenstone pebble)

Serpentinite, composed mainly of serpentine-group minerals (e.g., lizardite, chrysotile, or antigorite)

AI-generated identification · may be incorrect

Olive-green with dark veins and a mottled, waxy-to-dull surface; serpentine minerals are Mohs 2.5–5.5, generally monoclinic or platy/fibrous. The image is not sharp enough to confirm mineral composition or hardness.

Identified September 28, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when water alters magnesium-rich ultramafic rocks, commonly during seafloor or subduction-zone metamorphism; its age depends on the source rock and cannot be determined from the photo.

Uses & applications

Serpentinite is used as decorative stone, carving material, and sometimes as a source of talc or asbestos-bearing minerals; this small pebble is primarily a collector specimen.

Geological facts

Green color and dark veining are common in serpentinite, but similar appearances occur in other altered rocks and minerals.

Field identification & locations

Look for a green, often waxy surface and softer, slick-feeling material; confirm with hardness and streak tests, since appearance alone is inconclusive. Serpentinite occurs in ultramafic belts worldwide.