Rock Identifier
Fossil coral (Colonial coral fossil; exact taxon cannot be determined from the image) — fossil
fossil

Fossil coral

Colonial coral fossil; exact taxon cannot be determined from the image

AI-generated identification · may be incorrect

Pale gray-tan, rough, with repeated radial corallite patterns. Fossil skeletons are commonly preserved as calcite (Mohs hardness 3) or silica; crystal structure and cleavage depend on the replacement mineral.

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Physical properties

Pale gray-tan, rough, with repeated radial corallite patterns. Fossil skeletons are commonly preserved as calcite (Mohs hardness 3) or silica; crystal structure and cleavage depend on the replacement mineral.

Formation & geological history

Formed from colonial coral skeletons in a marine reef, later buried and fossilized by mineral replacement or sediment infill. Age cannot be established from appearance alone; fossil corals span hundreds of millions of years.

Uses & applications

Used as a collectible and sometimes as decorative stone or jewelry material; fossil coral may also be cut and polished.

Geological facts

The star-shaped structures are individual corallites, the skeletal cups of coral polyps.

Field identification & locations

Identify by the repeated radial septa and tightly packed coral cups, unlike the irregular pores of many other fossils. Fossil corals occur in sedimentary rocks worldwide; locality and age require geological context.

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Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil