sedimentary

Polished fossiliferous limestone

Micritic limestone, likely bioclastic/fossiliferous calcite (CaCO₃)

AI-generated identification · may be incorrect

Hardness about 3 Mohs; gray-brown, cream, and reddish mottling with dull to waxy polish, fine-grained texture, and visible fossil or pore-like structures. Calcite has rhombohedral cleavage, though crystals are not obvious in this polished piece; specific gravity is about 2.7.

Identified August 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented carbonate mud and marine shell or skeletal debris, commonly in shallow ancient seas. Its precise geological age cannot be determined from the photograph and may range from Paleozoic to Cenozoic.

Uses & applications

Used as a decorative cabochon, paperweight, and lapidary specimen; limestone is also important for cement, aggregate, and building stone.

Geological facts

The rounded shape and reflective surface indicate tumbling or polishing rather than natural weathering. Fossil-rich limestone may react vigorously with dilute hydrochloric acid or vinegar, producing fizz.

Field identification & locations

Identify it by its low hardness, carbonate reaction, fine sedimentary texture, and fossil/pore patterns; common sources include marine limestone deposits worldwide. Avoid prolonged acid testing on polished surfaces.