sedimentary

Rounded limestone pebble

Limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Light cream-gray, fine-grained, dull to faintly sugary luster, and roughly spherical from abrasion; calcite hardness is Mohs 3, with possible weak fizz in dilute hydrochloric acid. Cleavage is not usually visible in the compact pebble.

Identified September 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented carbonate mud or shell debris, then rounded by water or wave transport; the exact geological age cannot be determined from the photograph. Commonly develops in shallow marine or freshwater carbonate environments.

Uses & applications

Used for aggregate, cement, lime, building stone, and soil neutralization; attractive rounded pieces are sold as landscaping or inexpensive collectible specimens.

Geological facts

Limestone can preserve fossils and may recrystallize into marble under heat and pressure. The smooth shape indicates prolonged transport or tumbling rather than its original depositional form.

Field identification & locations

Likely identifiable by its pale color, fine texture, relatively low hardness, and acid effervescence; common in limestone regions, riverbeds, beaches, and gravel deposits. A steel nail will not scratch it easily, while a knife may scratch it.