metamorphic

Tumbled greenstone (likely serpentine-rich)

Serpentinite or chlorite/epidote-rich greenstone; exact identification requires testing

AI-generated identification · may be incorrect

Smooth, rounded, mottled green-and-black stone with a subdued to waxy luster. Likely hardness about 3–6 Mohs depending on composition; fine-grained, with no obvious crystals or cleavage visible.

Identified October 13, 2026More metamorphic →

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Physical properties

Smooth, rounded, mottled green-and-black stone with a subdued to waxy luster. Likely hardness about 3–6 Mohs depending on composition; fine-grained, with no obvious crystals or cleavage visible.

Formation & geological history

Formed when magnesium-rich ultramafic rock was altered by water and/or low-grade metamorphism; such rocks occur in ancient oceanic crust and mountain belts. The image cannot establish its geological age or exact mineral makeup.

Uses & applications

Commonly tumbled for collecting, crafts, and inexpensive jewelry; serpentinite is also used as decorative building stone.

Geological facts

“Greenstone” is a broad field term for several green metamorphic rocks, not a single mineral. Similar-looking tumbled stones can include serpentinite, chlorite schist, or other altered rocks.

Field identification & locations

The green color and dark streaks suggest a serpentine- or chlorite-bearing rock, but appearance alone is inconclusive; hardness, streak, and specific-gravity tests can help distinguish it. Similar rocks occur worldwide in metamorphic belts.