metamorphic
Greenstone (likely chlorite-rich metamorphic rock)
Greenstone; commonly altered mafic rock composed of chlorite, actinolite, epidote, and albite
AI-generated identification · may be incorrectDark green, fine- to medium-grained, with a faint sparkle; typically Mohs 5–6, vitreous to dull, and lacking prominent cleavage. The image alone does not allow reliable mineral or density testing.
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Physical properties
Dark green, fine- to medium-grained, with a faint sparkle; typically Mohs 5–6, vitreous to dull, and lacking prominent cleavage. The image alone does not allow reliable mineral or density testing.
Formation & geological history
Forms when basalt or other mafic volcanic rock is metamorphosed or hydrothermally altered, commonly in ancient oceanic crust and greenstone belts. Such rocks occur across a wide range of geological ages.
Uses & applications
Used as crushed aggregate, landscaping stone, and occasionally carved or polished for ornaments; gem-quality material is uncommon.
Geological facts
“Greenstone” is a field term for green-colored altered mafic rock, not one single mineral or precisely defined composition.
Field identification & locations
The dark green color and granular texture fit greenstone, but a definitive identification would require examining a fresh surface and testing mineral composition. Common in metamorphic belts worldwide, including Canada, Australia, and parts of Africa.
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