sedimentary

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Gray-brown, fine-grained carbonate matrix containing rounded fossil fragments or shell sections; typically Mohs 3, dull to faintly chalky luster, massive structure, and weak/no cleavage. It should effervesce strongly with dilute hydrochloric acid or vinegar if calcite-rich.

Identified August 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells and skeletal debris accumulate, are compacted, and cemented on shallow seafloors; age may range from Paleozoic to Cenozoic depending on locality. The visible inclusions appear fossil-like, though the photograph is not sufficient for precise identification.

Uses & applications

Used as building stone, aggregate, cement and lime feedstock; attractive pieces are collected or made into decorative specimens. Ordinary hand specimens generally have little commercial value.

Geological facts

Fossiliferous limestone can preserve brachiopods, bivalves, crinoids, corals, or gastropods, and the fossils may weather in relief from the matrix.

Field identification & locations

Common in former marine sedimentary basins worldwide, including the British Isles, Mediterranean, North America, and Southeast Asia. Confirm by acid testing, examining shell symmetry and internal structure with a lens, and checking that it is not concrete or slag.