metamorphic

Serpentine (likely serpentinite)

Serpentine-group minerals, chiefly antigorite, lizardite, and/or chrysotile; commonly with magnetite and minor brucite

AI-generated identification · may be incorrect

Dark olive-green to black, waxy to greasy luster, massive and fine-grained with irregular fractures; Mohs hardness about 2.5–4, generally noncleavable, specific gravity roughly 2.5–2.6. The rounded, polished-looking surface is consistent with weathering or handling.

Identified September 22, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic rocks such as peridotite undergo hydration and metamorphism, commonly in oceanic crust and subduction-zone mélanges. Ages vary widely; the specimen’s age cannot be determined from the photograph.

Uses & applications

Used as ornamental and carving stone, green building stone, and historically for decorative objects; lapidary material is occasionally sold as “serpentine jade.” Avoid cutting or sanding unknown material because some serpentine can contain asbestos-form chrysotile.

Geological facts

Serpentine is a mineral group rather than one single mineral. Magnetite commonly gives serpentinite a dark color and may produce weak attraction to a magnet.

Field identification & locations

Look for olive-green color, waxy texture, low hardness, smooth curved fracture, and possible dark magnetite specks; a streak, hardness, magnetism, and asbestos testing help confirm it. Common in California, the Appalachians, the Alps, New Zealand, and oceanic terranes worldwide.