sedimentary

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Tan-gray, fine-grained carbonate matrix containing abundant pale shell or crinoid fragments; typically Mohs 3, dull to subtly sugary luster, with calcite cleavage. It should fizz briskly with dilute hydrochloric acid or vinegar, especially on a freshly broken surface.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

A shallow-marine sedimentary rock formed from accumulated and cemented skeletal debris, commonly during the Paleozoic or Mesozoic eras; exact age cannot be determined from the photograph. Burial compaction and calcite cement lithified the sediment.

Uses & applications

Used as crushed aggregate, road base, cement and lime feedstock, building stone, and educational or amateur fossil specimens; this piece has modest decorative and collecting value.

Geological facts

The visible rounded and irregular inclusions are likely fossil fragments rather than true mineral crystals, possibly shell pieces or crinoid debris. Weathering can preferentially expose fossils and produce a rough surface.

Field identification & locations

Common in marine limestone belts worldwide, including the United States, Europe, and parts of Asia. Identify it by visible bioclasts, relatively low hardness, and acid reaction; a lab test is needed for precise fossil and age identification.