metamorphic

Polished dark green-black stone, likely serpentinite

Serpentinite (serpentine-group minerals; commonly antigorite, lizardite, and chrysotile)

AI-generated identification · may be incorrect

Fine-grained, rounded and polished, with a dark green-black color and subtle mottling. Serpentine minerals have Mohs hardness of about 2.5–4, a waxy to dull luster, and monoclinic or triclinic crystal structures; the image alone cannot confirm identification.

Identified September 25, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic rocks are altered by water during low-temperature metamorphism, often near tectonic plate boundaries. Such alteration occurs across geological ages.

Uses & applications

Serpentinite is used as an ornamental and carving stone; some varieties are cut or polished for decorative objects and jewelry.

Geological facts

Its name comes from its often snake-like mottled appearance. The pictured specimen’s smooth, nearly spherical shape suggests it has been shaped and polished.

Field identification & locations

Look for green mottling, a relatively soft feel, and a waxy luster; common sources include ophiolite belts and serpentinite bodies worldwide. Confirm with mineral or hardness testing, since several dark stones can look similar.