metamorphic

Greenstone (likely chlorite- or epidote-rich metamorphic rock)

Greenstone; commonly metamorphosed basalt or dolerite, with chlorite, epidote, and actinolite

AI-generated identification · may be incorrect

Dark olive-green, fine-grained, with a granular to slightly sparkly surface; likely Mohs 5–6, though exact hardness and mineral content cannot be confirmed from the image. Greenstone has no single crystal structure or characteristic cleavage because it is a mixture of minerals.

Identified October 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when basaltic rocks are altered by low-grade metamorphism and hydrothermal fluids. Such rocks occur in ancient volcanic belts of many geological ages.

Uses & applications

Used as decorative stone, landscaping material, and occasionally for carvings or jewelry; ordinary hand specimens have little commercial value.

Geological facts

The name “greenstone” describes color and alteration, not one precise mineral or rock composition.

Field identification & locations

Look for a dense, fine-grained green rock, often with tiny pale or dark mineral flecks; it may occur in metamorphic belts and altered volcanic terrains. Image-based identification is tentative; a hardness test or thin-section analysis would help distinguish it from other green rocks.