sedimentary

Rounded limestone pebble

Limestone; predominantly calcite (CaCO₃), possibly micritic or fossiliferous

AI-generated identification · may be incorrect

Cream-tan, smooth water-worn surface with fine granular texture and scattered darker grains; typically Mohs 3, dull to faintly waxy luster, microcrystalline calcite, and no obvious cleavage. It should fizz vigorously with dilute hydrochloric acid or household vinegar if calcitic.

Identified August 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed from compacted carbonate mud, shells, or skeletal debris, then rounded by stream, beach, or glacial transport. Its exact age cannot be determined from the photograph; limestone ranges from Precambrian to modern geological deposits.

Uses & applications

Used as aggregate, cement and lime feedstock, dimension stone, and landscaping material; attractive polished pieces may be sold as inexpensive curios or cabochons.

Geological facts

The specimen’s rounded, flattened shape indicates abrasion during transport. Dark specks may be fossil fragments, impurities, or weathering stains.

Field identification & locations

Common in carbonate terrains and river or beach gravels worldwide; distinguish it from quartzite by its softness and acid reaction, and from concrete by its natural texture and lack of uniform cement paste.