sedimentary

Fossiliferous limestone pebble

Bioclastic limestone, chiefly calcite (CaCO₃), possibly containing small fossil fragments

AI-generated identification · may be incorrect

Gray-beige, fine-grained, dull to slightly waxy surface with rounded stream-worn form and visible shell-like markings. Calcite-rich limestone has Mohs hardness 3, poor cleavage in aggregate, and reacts with dilute hydrochloric acid; specific gravity is about 2.3–2.7.

Identified August 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented marine carbonate mud and skeletal debris, commonly deposited during Paleozoic–Mesozoic seas, then rounded by erosion in a stream or beach environment. The precise age cannot be determined from the photograph.

Uses & applications

Primarily a teaching, collecting, and lapidary specimen; limestone is widely used for cement, aggregate, building stone, and agricultural lime. It is generally not gem-quality.

Geological facts

The circular pale marking may be a fossil fragment, cavity, or mineral-filled structure, but the image alone cannot confirm its identity. Fossiliferous limestones often preserve shells, crinoids, bryozoans, or corals.

Field identification & locations

Look for visible fossils, a sugary or earthy texture, and vigorous fizz with dilute acid; avoid acid testing valuable specimens. Common worldwide in former shallow-marine basins and as rounded gravel in waterways.