fossil

Fossiliferous limestone with colonial coral fossils

Calcitic limestone; probable fossil tabulate or rugose coral (Class Anthozoa)

AI-generated identification · may be incorrect

Mostly calcite (CaCO₃), gray-white to tan and rusty brown, with abundant polygonal to rounded corallite cavities; hardness about 3, vitreous to dull luster, massive structure, and weak rhombohedral calcite cleavage. Acid typically fizzes strongly.

Identified August 23, 2026More fossil →

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Physical properties

Formation & geological history

A marine carbonate sediment deposited in a shallow, warm sea, later lithified and partly weathered or recrystallized. The fossils may be Paleozoic, commonly Devonian–Carboniferous (about 419–299 million years old), but exact age requires locality data.

Uses & applications

Used as decorative stone, teaching specimens, and geological collectibles; limestone is also widely used for cement, aggregate, lime, and building stone.

Geological facts

The repeated cups or tubes are fossil corallites, representing individual coral polyps in a colony; irregular cavities may reflect weathering or dissolved fossil material.

Field identification & locations

Identify it by the repeated coral-cup pattern and calcite reaction, distinguishing it from vesicular volcanic rock. Common in exposed Paleozoic marine carbonate formations worldwide; value is usually $5–$40, or roughly $50–$150 for a large, exceptionally preserved specimen.