fossil

Fossilized coral or reef limestone

Calcite (CaCO₃), commonly fossil coral such as Scleractinia

AI-generated identification · may be incorrect

Cream-to-tan, porous, irregular specimen with visible corallite-like cavities and shell/reef textures; calcite has Mohs hardness 3, vitreous-to-dull luster, rhombohedral cleavage, and specific gravity about 2.7. It should fizz readily in dilute hydrochloric acid or strong vinegar if exposed calcite is present.

Identified September 10, 2026More fossil →

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Physical properties

Formation & geological history

A biological carbonate skeleton accumulated in a shallow marine reef, was buried, lithified, and mineral-replaced or cemented by calcite. Its precise geological age cannot be determined from the image; fossil corals range from Paleozoic to modern geological deposits.

Uses & applications

Used mainly as a teaching or collecting specimen; crushed fossil limestone may serve as aggregate or lime feedstock, though this piece is better suited for display.

Geological facts

The branching or honeycomb textures are fossilized skeletal structures, not crystal growth. Weathering can obscure the original coral morphology and make identification difficult.

Field identification & locations

Common in former reef and limestone regions worldwide, including Florida, the Caribbean, Mediterranean, and parts of Europe and Asia. Confirm with acid reaction, close inspection of repeated corallite patterns, and a professional paleontological comparison.