metamorphic
Greenstone (likely chlorite-rich metamorphic rock)
Greenschist; commonly composed of chlorite, actinolite, and epidote, with possible albite
AI-generated identification · may be incorrectFine-grained, mottled pale green and gray, with a dull to slightly silky luster and no obvious cleavage. Hardness is typically about 4–6 Mohs; exact composition cannot be confirmed from the image alone.
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Physical properties
Fine-grained, mottled pale green and gray, with a dull to slightly silky luster and no obvious cleavage. Hardness is typically about 4–6 Mohs; exact composition cannot be confirmed from the image alone.
Formation & geological history
Forms when mafic igneous rocks such as basalt are altered by low-grade regional metamorphism and hydrothermal fluids. Such rocks occur in geological terrains of many ages.
Uses & applications
Used as a decorative or carving stone and collected as a mineral specimen; larger quantities may serve as local building stone.
Geological facts
“Greenstone” is a broad field term for green-hued, altered rocks, not a single mineral or precisely defined composition.
Field identification & locations
The small rough fragment’s green color and fine-grained appearance fit greenstone, but visual identification is uncertain. Look for a consistently green interior and fine foliation or tiny actinolite crystals; common in metamorphic belts worldwide.
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