sedimentary

Rounded limestone pebble

Calcite-rich limestone (CaCO₃)

AI-generated identification · may be incorrect

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.

Identified August 26, 2026More sedimentary →

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Physical properties

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.