sedimentary

Polished fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃), with fossil shell fragments

AI-generated identification · may be incorrect

Typically Mohs hardness 3, cream to tan, with a dull to waxy or polished luster; visible rounded fossil cavities and shell textures occur in a fine calcite matrix. Calcite has rhombohedral cleavage and reacts vigorously with dilute hydrochloric acid or vinegar.

Identified September 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells and skeletal debris accumulate, compact, and cement on shallow seafloors; age cannot be determined from the image and may range from Paleozoic to Cenozoic. The specimen appears cut or tumbled and polished.

Uses & applications

Used as building and decorative stone, aggregate, cement feedstock, and occasionally as a fossil-collecting or ornamental specimen; not generally suitable for durable jewelry because calcite is soft.

Geological facts

The rounded structures may be fossil shells, bryozoans, or other marine organisms, but exact identification requires magnification and locality data. Acid effervescence distinguishes calcite-rich limestone from many look-alikes.

Field identification & locations

Common in former shallow-marine sedimentary basins worldwide, including Florida, Indiana, England, and parts of the Mediterranean. Look for fossils, granular texture, low hardness, and acid reaction; avoid confusing it with polished concrete or aragonite-rich stone.