sedimentary

Fossiliferous limestone

Calcite-rich limestone (CaCO₃), likely bioclastic limestone

AI-generated identification · may be incorrect

Cream-white to tan, coarse and irregular, with abundant fossil or shell-like cavities and weathered brown iron-oxide staining. Calcite has Mohs hardness 3, vitreous to dull luster, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid; the specimen is likely massive rather than crystalline.

Identified August 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells, skeletal fragments, and carbonate mud accumulate, compact, and cement on a shallow seafloor. Its precise age cannot be determined from the photograph and requires fossil identification or laboratory dating.

Uses & applications

Used as crushed stone, aggregate, cement and lime feedstock, and occasionally as decorative or educational material. This attractive fossil-bearing piece has modest collector value.

Geological facts

The rounded cavities may represent dissolved shells, molds, or corals, while brown coloration commonly reflects iron oxides. A vinegar test may produce weak fizz, but dilute hydrochloric acid is more diagnostic.

Field identification & locations

Common in marine sedimentary basins worldwide, including limestone belts in North America, Europe, and Asia. Look for visible fossil fragments, soft calcite surfaces, and acid effervescence; avoid confusing it with weathered concrete.