metamorphic

Greenstone / altered mafic rock

Likely serpentinite or chlorite-rich metabasalt; exact identification requires testing

AI-generated identification · may be incorrect

Dark green, opaque, fine-grained, and dull to weakly waxy; likely Mohs 3–6, with little visible crystal structure and irregular fracture. The rounded shape may reflect natural weathering or human tumbling.

Identified September 21, 2026More metamorphic →

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Physical properties

Formation & geological history

Probably formed by low- to moderate-grade alteration or metamorphism of basalt or ultramafic rock, commonly during oceanic crust alteration; age depends on its source locality.

Uses & applications

Used as decorative stone, carving material, landscaping rock, and occasionally jewelry or polished lapidary material; it has limited value as an unverified hand specimen.

Geological facts

Green color commonly comes from chlorite, serpentine, epidote, or actinolite. A streak, hardness, specific-gravity, and acid test would help distinguish serpentinite from chlorite-rich basalt.

Field identification & locations

Common in ophiolites, metamorphic belts, and areas of hydrothermal alteration worldwide. Check for a soapy feel, fibrous texture, magnetism, and white-to-green streak; avoid cutting unknown serpentinite because some varieties may contain asbestos minerals.