metamorphic

Greenstone (likely chlorite schist)

Chlorite-rich metamafic rock; commonly chlorite + actinolite/epidote with quartz and feldspar

AI-generated identification · may be incorrect

Dark green-gray, fine- to medium-grained, with a sparkly, foliated surface. Hardness varies roughly 3–6 Mohs depending on minerals; exact composition cannot be confirmed from the image.

Identified October 8, 2026More metamorphic →

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Physical properties

Dark green-gray, fine- to medium-grained, with a sparkly, foliated surface. Hardness varies roughly 3–6 Mohs depending on minerals; exact composition cannot be confirmed from the image.

Formation & geological history

Forms when basalt or other mafic rock is altered by low-grade regional metamorphism and hydrothermal fluids. Such rocks occur in geological terranes of many ages.

Uses & applications

Mostly collected as a field specimen or used locally as decorative or building stone; this small rough piece has little commercial value.

Geological facts

“Greenstone” is a broad field term for green-hued metamorphosed mafic rocks, not a single mineral or precisely defined rock type.

Field identification & locations

Look for a green color, fine grains, and a foliated or schistose texture; common in ancient volcanic belts and metamorphic terrains worldwide. The visible sparkle and texture suggest chlorite-rich schist, but a closer examination or mineral tests would be needed for identification.