metamorphic
Water-worn greenstone pebble
Greenstone (metamorphosed mafic volcanic rock; commonly chlorite–actinolite–epidote-bearing metabasalt)
AI-generated identification · may be incorrectFine-grained, rounded pebble with muted blue-green and tan weathered surfaces; typically Mohs 5–6, dull to slightly waxy, with no visible cleavage. Exact mineral composition cannot be confirmed from the image.
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Physical properties
Fine-grained, rounded pebble with muted blue-green and tan weathered surfaces; typically Mohs 5–6, dull to slightly waxy, with no visible cleavage. Exact mineral composition cannot be confirmed from the image.
Formation & geological history
Likely formed when basalt or related mafic lava was altered by low-grade metamorphism and later rounded by stream or shoreline transport; its age and source cannot be determined visually.
Uses & applications
Greenstone is used as dimension or aggregate stone and sometimes carved or collected as a decorative pebble; this specimen appears mainly suitable for collecting.
Geological facts
“Greenstone” describes color and alteration rather than one precise composition, and can refer to rocks formed in ancient volcanic belts.
Field identification & locations
Look for a dense, fine-grained texture and green alteration minerals; hardness and a fresh broken surface help distinguish it from softer rocks. Greenstones occur in metamorphic belts worldwide.
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