fossil

Fossilized coral (porous coral limestone)

Fossil coral, commonly colonial scleractinian coral preserved as calcite/aragonite (CaCO₃)

AI-generated identification · may be incorrect

Typically brown to gray, highly porous with coralite cavities and calcite-filled openings; Mohs hardness about 3–4, dull to waxy luster, with no prominent cleavage. The regular hole pattern reflects fossilized coral structures rather than volcanic vesicles.

Identified September 9, 2026More fossil →

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Physical properties

Formation & geological history

A colonial coral reef was buried and lithified as carbonate sediment, with original aragonite commonly recrystallized to calcite; age may range from Paleozoic to Cenozoic depending on locality. Weathering or partial dissolution accentuates the pores.

Uses & applications

Used as a teaching and lapidary specimen, ornamental stone, and occasionally in polished décor; it is generally unsuitable for structural construction because of its softness and porosity.

Geological facts

Corallite openings may preserve individual coral polyps and septa, revealing ancient reef ecosystems. Acid can weakly fizz on fresh surfaces because the material is carbonate.

Field identification & locations

Found in uplifted reef limestones worldwide, including Florida, the Caribbean, Southeast Asia, and Pacific islands. Identify it by repeated coral-cell geometry, carbonate hardness, and acid reaction; exact species requires microscopy.