sedimentary

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Dark gray, fine- to medium-grained carbonate rock containing abundant shell or fossil fragments; calcite has Mohs hardness 3, vitreous to dull luster, rhombohedral cleavage, and specific gravity about 2.7. The pale material appears to be fossilized shell or calcite veins.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine organisms accumulate, are compacted, and cemented on ancient seafloors; age cannot be determined reliably from the photograph and may range from Paleozoic to Cenozoic. It may have undergone minor recrystallization or weathering.

Uses & applications

Used as aggregate, cement and lime feedstock, dimension stone, and ornamental material; fossiliferous pieces are mainly collected for education and display rather than jewelry.

Geological facts

Acid testing is diagnostic: dilute hydrochloric acid or vinegar may visibly fizz on fresh surfaces because of calcite. Fossil shape and preservation can help determine its age and depositional environment.

Field identification & locations

Common in marine sedimentary basins worldwide, including limestone belts in Europe, North America, and Asia. Identify by soft, carbonate-rich matrix, visible fossils, and fizzing; avoid damaging valuable specimens with acid.