fossil

Coral limestone / fossil coral

Calcitic fossil coral, commonly Scleractinia; CaCO₃

AI-generated identification · may be incorrect

Cream-white, highly porous, irregularly knobby specimen with dull to slightly sugary luster; calcite hardness is Mohs 3, with poor cleavage and specific gravity around 2.7. The visible corallite pits and honeycomb-like structure suggest fossilized coral rather than volcanic pumice.

Identified August 16, 2026More fossil →

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Physical properties

Formation & geological history

Marine coral skeletons accumulated on ancient reefs and were mineralized or preserved as calcite during burial and diagenesis, commonly in Paleozoic–Cenozoic limestones. Exact age cannot be determined from the photograph.

Uses & applications

Used mainly as a teaching, display, and collecting specimen; coral limestone can be quarried for aggregate, cement, lime, and decorative stone. It has little jewelry value unless cut and polished.

Geological facts

Calcitic coral fossils retain the original colony architecture, including individual corallites (polyp chambers). Acid typically causes vigorous effervescence because the specimen is calcium carbonate.

Field identification & locations

Common in uplifted marine limestones worldwide, including Florida, the Caribbean, Australia, and parts of Europe and Asia. Confirm with a 10% hydrochloric-acid or vinegar test, observing fizz on a fresh surface; avoid damaging valuable specimens.