metamorphic
Water-worn pebble, likely greenstone
Greenstone (metamorphosed mafic volcanic rock; commonly chlorite-, actinolite-, and epidote-bearing)
AI-generated identification · may be incorrectRounded, fine-grained, dull gray-green surface with darker and rusty patches. Typical greenstone minerals have Mohs hardness about 5–6; exact hardness, composition, and crystal texture cannot be confirmed from the photo.
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Physical properties
Rounded, fine-grained, dull gray-green surface with darker and rusty patches. Typical greenstone minerals have Mohs hardness about 5–6; exact hardness, composition, and crystal texture cannot be confirmed from the photo.
Formation & geological history
Likely a mafic volcanic rock altered by low-grade metamorphism and rounded by water or abrasion. Its age and precise formation environment cannot be determined visually.
Uses & applications
Greenstone is used as crushed aggregate, building stone, and occasionally for carved or decorative objects; this pebble is mainly a collecting or display specimen.
Geological facts
“Greenstone” is a broad field term for green-hued, metamorphosed mafic rocks, not one uniquely defined mineral or composition.
Field identification & locations
The smooth, rounded shape indicates transport or abrasion, while the muted green color is consistent with chlorite or related alteration minerals. Greenstones occur in metamorphic belts worldwide; a fresh surface and hardness test would help distinguish it from other dark pebbles.
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