fossil

Coral fossil (likely fossilized reef coral)

Calcitic coral; commonly fossilized Scleractinia or related colonial coral

AI-generated identification · may be incorrect

Cream-white, dull to weakly waxy, highly porous surface with polygonal-to-rounded corallite cavities; composed mainly of calcite, commonly pseudomorphing original aragonite. Mohs hardness about 3–4; no obvious cleavage; specific gravity roughly 2.6–2.8.

Identified September 21, 2026More fossil →

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Physical properties

Formation & geological history

A colonial marine coral skeleton accumulated in a warm, shallow reef and was later buried and mineralized, often during the Paleozoic–Cenozoic. The apparent cavities are individual corallites or partially weathered skeletal structures.

Uses & applications

Primarily a teaching and collecting specimen; polished fossil coral is used decoratively and occasionally in jewelry. It is not typically suitable for construction because of its porosity and softness.

Geological facts

Fossil corals can preserve colony growth patterns and ancient reef environments. Acid testing may produce vigorous fizzing if the material is calcite, though porous surfaces can make the result uneven.

Field identification & locations

Commonly found in limestone beds and uplifted former reef regions worldwide, including Florida, the Great Lakes region, the Caribbean, Australia, and parts of Europe. Distinguish it from pumice or weathered limestone by repeated corallite patterns and carbonate fizz.