fossil

Fossiliferous limestone, likely coral or shell-rich limestone

Biogenic calcite (CaCO₃), commonly limestone containing fossil coral or mollusks

AI-generated identification · may be incorrect

Typically Mohs hardness 3, white to tan or gray, dull to earthy luster, and irregular granular texture; calcite may show rhombohedral cleavage. The visible porous cavity and rounded fossil textures suggest a biogenic limestone rather than a crystalline mineral.

Identified August 29, 2026More fossil →

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Physical properties

Formation & geological history

Formed from accumulated marine skeletal material that lithified into limestone, commonly during Paleozoic–Cenozoic shallow-marine deposition; the cavity may reflect dissolved fossils or weathering.

Uses & applications

Used as aggregate, cement and dimension stone when sound; attractive fossiliferous pieces are mainly collected or displayed rather than used in jewelry.

Geological facts

Calcite-rich limestone effervesces vigorously with dilute hydrochloric acid or household vinegar, though vinegar may react slowly. Coral fossils often preserve repeated corallite pores or honeycomb-like structures.

Field identification & locations

Common in former shallow seas worldwide, including Florida, the Caribbean, Mediterranean regions and many coastal sedimentary basins. Check for acid reaction, low hardness, and identifiable fossil patterns; avoid assuming every hole is a fossil cavity.