metamorphic

Likely greenstone (metamorphosed mafic rock)

Greenstone; commonly chlorite–actinolite–epidote–albite assemblage

AI-generated identification · may be incorrect

Fine-grained, dull green-gray, with a granular or subtly sparkling surface; likely Mohs 5–6. Exact mineral makeup and properties cannot be confirmed from the photo alone.

Identified October 14, 2026More metamorphic →

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Physical properties

Fine-grained, dull green-gray, with a granular or subtly sparkling surface; likely Mohs 5–6. Exact mineral makeup and properties cannot be confirmed from the photo alone.

Formation & geological history

Typically forms when basalt or other mafic volcanic rock is altered by low-grade metamorphism and hydrothermal fluids. Its age depends on the source formation and cannot be determined visually.

Uses & applications

Used as decorative or landscape stone and collected as a field specimen; some varieties are carved or polished.

Geological facts

“Greenstone” is a broad field term for green-hued metamorphosed mafic rock, not one fixed mineral species.

Field identification & locations

The specimen appears rough, compact, and green-gray, consistent with greenstone, but a photo cannot distinguish it reliably from other rocks. Greenstones occur in ancient volcanic belts worldwide; a fresh surface and mineral tests can improve identification.