Rock Identifier
Fossilized Coral (Rugosa or Tabulata coral fossil (SiO2)) — fossil
fossil

Fossilized Coral

Rugosa or Tabulata coral fossil (SiO2)

AI-generated identification · may be incorrect

Hardness of 6.5 to 7 on the Mohs scale, typically gray, brown, or tan with distinct star-shaped or honeycomb cellular patterns, and vitreous to dull luster.

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Physical properties

Hardness of 6.5 to 7 on the Mohs scale, typically gray, brown, or tan with distinct star-shaped or honeycomb cellular patterns, and vitreous to dull luster.

Formation & geological history

Formed in ancient shallow marine environments when prehistoric coral skeletons were replaced by silica-rich groundwater over millions of years.

Uses & applications

Used primarily in lapidary arts, making cabochons for jewelry, and valued as a collectible geological specimen.

Geological facts

Also known as Petoskey stone in certain regions, these fossils record marine ecosystems dating back hundreds of millions of years to the Paleozoic Era.

Field identification & locations

Identify by characteristic cellular corallite patterns and hardness; commonly found in limestone-rich regions and ancient seabeds worldwide.

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

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Weathered fossil bone fragment (identification uncertain)

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

fossil