igneous
Greenstone pebble (possibly altered basalt)
Chlorite- and/or epidote-altered basalt; exact identification requires testing
AI-generated identification · may be incorrectSmall, dull pale-green fragment with a fine-grained, mottled surface. If altered basalt, it is mostly plagioclase and pyroxene replaced partly by chlorite or epidote; hardness and crystal structure cannot be determined reliably from the image.
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Physical properties
Small, dull pale-green fragment with a fine-grained, mottled surface. If altered basalt, it is mostly plagioclase and pyroxene replaced partly by chlorite or epidote; hardness and crystal structure cannot be determined reliably from the image.
Formation & geological history
Likely a fragment of basalt altered by low-grade metamorphism or hydrothermal fluids, then rounded by weathering. Its geological age and source cannot be established from the photograph.
Uses & applications
This size and appearance are mainly of interest as a casual field or teaching specimen; greenstone is also used locally as building or decorative stone.
Geological facts
“Greenstone” is a broad field term for green-hued, altered mafic rock, not a single mineral or precise rock species.
Field identification & locations
A green color and fine-grained texture fit altered basalt, but similar-looking minerals and manufactured fragments are possible; inspect a fresh surface and test hardness or streak for confirmation. Such rocks occur in ancient volcanic belts worldwide.
