fossil

Polished fossiliferous limestone, likely fossil shell fragment

Calcite-rich limestone (CaCO₃), possibly bioclastic/coquina limestone

AI-generated identification · may be incorrect

Cream, tan, brown, and gray mottling with curved, layered fossil structures and a polished surface; calcite has Mohs hardness 3, vitreous to pearly luster, rhombohedral cleavage, and specific gravity about 2.7. Effervesces strongly with dilute hydrochloric acid.

Identified September 6, 2026More fossil →

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Physical properties

Formation & geological history

Formed from compacted and cemented marine shell material or carbonate mud, commonly during the Paleozoic–Cenozoic; recrystallization may obscure individual fossils. The exact age and fossil identity require microscopy or locality information.

Uses & applications

Used as a decorative polished specimen, lapidary material, and educational fossil; limestone is also widely used for cement, aggregate, and building stone. Jewelry use is occasional because calcite is relatively soft.

Geological facts

The visible swirled bands may represent shell chambers, growth layers, or recrystallized bioclasts rather than mineral veins. Polishing can make fossil textures appear more strongly contrasted.

Field identification & locations

Identify by curved biological layering, low hardness, and acid reaction; distinguish it from marble by visible fossil textures and generally non-crystalline appearance. Common in marine sedimentary basins worldwide.