metamorphic

Tumbled greenstone, likely serpentine

Serpentinite; mainly antigorite/lizardite/chrysotile, Mg₃Si₂O₅(OH)₄

AI-generated identification · may be incorrect

Dark to gray-green, mottled and waxy with a dull-to-subvitreous luster; commonly massive rather than visibly crystalline. Hardness is typically 2.5–4 Mohs, with no prominent cleavage and specific gravity around 2.5–2.6.

Identified September 6, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks, especially peridotite, undergo hydration and low-temperature metamorphism. Serpentinite is common in ancient oceanic crust and tectonic suture zones, ranging from Precambrian to modern geological settings.

Uses & applications

Used as ornamental stone, carvings, beads, cabochons, and tumbled specimens; massive serpentinite has limited architectural use. Fibrous chrysotile varieties can be asbestos-bearing and should not be cut, drilled, or powdered.

Geological facts

The photograph is consistent with polished or naturally worn serpentinite, though greenstone, nephrite, or altered basalt are possible without testing. A streak, hardness, density, and thin-section examination would improve identification.

Field identification & locations

Commonly found in ophiolites and fault zones, including California, Italy, New Zealand, Canada, and the Ural Mountains. It is usually softer and more waxy than jade; it may scratch with a steel knife, unlike nephrite.