sedimentary

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3, pale gray-beige color, earthy to dull luster, and no consistent cleavage. The visible shell and crinoid-like fragments are fossil debris cemented in a carbonate matrix; dilute hydrochloric acid should effervesce strongly.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when marine shells and skeletal material accumulated on an ancient seafloor, lithified by compaction and calcite cementation. Exact age is uncertain from the image, but such limestone commonly ranges from Paleozoic to Cenozoic.

Uses & applications

Used as crushed aggregate, cement and lime feedstock, dimension stone, and educational or decorative fossil specimens. Collectible value is usually modest unless fossils are exceptionally preserved or locality-specific.

Geological facts

The specimen is a bioclastic or coquina-like limestone containing abundant fragmented marine fossils, likely brachiopods, bivalves, crinoids, or bryozoans. Fossil-rich limestone records former shallow, oxygenated marine environments.

Field identification & locations

Common in former shallow seas worldwide, including the United States, United Kingdom, Europe, and parts of Asia. Identify it by abundant shell fragments, relatively soft carbonate matrix, and acid reaction; avoid confusing it with cemented shell-bearing concrete.