metamorphic

Polished greenstone pebble

Likely serpentinite (serpentine-group minerals); identification from appearance alone is uncertain

AI-generated identification · may be incorrect

Olive to dark green, smooth polished surface with a waxy-to-subvitreous luster and pale veins. Serpentine minerals have Mohs hardness about 2.5–4; crystal structure varies by mineral, and the pebble’s hardness and composition cannot be confirmed visually.

Identified October 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Serpentinite forms when water alters ultramafic rocks, commonly in oceanic crust and subduction zones; its age depends on the source rock. The rounded shape suggests natural abrasion before polishing.

Uses & applications

Used for carvings, beads, decorative objects, and ornamental stone; softer varieties are not suitable for heavy-wear jewelry.

Geological facts

“Greenstone” is a broad appearance-based name and can also refer to other rocks, including chlorite-rich metamorphic rocks.

Field identification & locations

Look for green color, a smooth or waxy feel, and possible pale veins; a hardness test or mineral analysis is needed to distinguish serpentinite from other green rocks. Serpentinite occurs in ultramafic-rock belts worldwide.