sedimentary

Weathered limestone pebble

Limestone; predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale gray to cream, fine-grained and dull to weakly earthy luster, with possible tiny fossil or shell fragments. Calcite hardness is about Mohs 3; it commonly effervesces strongly with dilute hydrochloric acid and has no visible cleavage at this grain size.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented carbonate mud, skeletal debris, or chemical carbonate precipitates, commonly in shallow marine environments. Its exact geological age cannot be determined from the photograph; weathering and rounding suggest transport in stream, beach, or glacial sediment.

Uses & applications

Used widely for aggregate, road stone, cement, lime, building stone, and agricultural soil treatment; this ordinary pebble has little jewelry value.

Geological facts

Limestone can recrystallize into marble during metamorphism and dissolve to form caves and karst landscapes. The specimen’s rounded shape and weathered surface indicate abrasion after formation.

Field identification & locations

Common worldwide, especially in former shallow-sea regions, river gravels, beaches, and limestone landscapes. Confirm with a fresh-surface acid test, reaction to vinegar, and a steel-knife scratch; identification is provisional because the image shows no diagnostic fossils or texture.