sedimentary

Weathered limestone or calcitic fossil-bearing rock

Calcite-rich limestone, primarily CaCO₃

AI-generated identification · may be incorrect

Pale gray to cream, dull earthy luster, porous and strongly weathered; calcite has Mohs hardness 3, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid or vinegar. The irregular cavity may represent a dissolved fossil, shell, or vug.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed as marine carbonate sediment that lithified during the Phanerozoic, then underwent groundwater dissolution and surface weathering; its exact age cannot be determined from the image.

Uses & applications

Common limestone is used for aggregate, cement, lime, building stone, and soil treatment; attractive fossiliferous pieces may be collected, but this specimen appears of modest commercial value.

Geological facts

Limestone commonly preserves marine fossils and develops karst cavities when acidic groundwater dissolves calcite.

Field identification & locations

Identify it by its light color, softness, porous texture, and acid fizz; inspect cavities for shell or fossil structures and test only an inconspicuous area. Common worldwide, especially in former shallow-marine regions.