sedimentary
Rounded limestone pebble
Calcite-rich limestone (CaCO₃)
AI-generated identification · may be incorrectTypically Mohs hardness 3, pale beige to gray, dull to weakly pearly luster, very fine-grained and massive with no visible cleavage; rounded surface indicates water abrasion. Exact identification is uncertain from an image alone.
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Physical properties
Typically Mohs hardness 3, pale beige to gray, dull to weakly pearly luster, very fine-grained and massive with no visible cleavage; rounded surface indicates water abrasion. Exact identification is uncertain from an image alone.
Formation & geological history
Limestone forms when carbonate mud, shells, or chemical precipitates lithify, commonly during the Paleozoic–Cenozoic; this specimen was likely transported and smoothed in a river, beach, or glacial deposit.
Uses & applications
Used for aggregate, cement, lime, building stone, and soil amendment; attractive polished pieces are used decoratively. This small pebble has little commercial value.
Geological facts
Calcite-rich limestone effervesces visibly with dilute hydrochloric acid or strong vinegar, though weathered surfaces may react weakly. It is softer than steel and can often be scratched with a knife.
Field identification & locations
Common worldwide, especially in marine sedimentary basins and stream gravels. Confirm with an acid test, Mohs scratch test, and inspection for fossil fragments or fine carbonate texture.
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