Rock Identifier
Fossilized Coral (Rugosa / Tabulata (Hexagonaria)) — fossil
fossil

Fossilized Coral

Rugosa / Tabulata (Hexagonaria)

AI-generated identification · may be incorrect

Hardness of 3-4 on the Mohs scale, typically brown, grey, or tan with distinct honeycomb or star-like corallite patterns, dull to sub-vitreous luster.

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Physical properties

Hardness of 3-4 on the Mohs scale, typically brown, grey, or tan with distinct honeycomb or star-like corallite patterns, dull to sub-vitreous luster.

Formation & geological history

Formed in ancient shallow tropical marine environments during the Paleozoic era when silica or calcite gradually replaced the original coral skeleton.

Uses & applications

Used primarily in lapidary arts, making decorative cabochons, polished display specimens, and as a collector's item.

Geological facts

Many fossilized corals are state symbols, such as Petoskey stone from Michigan, which dates back over 350 million years.

Field identification & locations

Easily identified by its unique cellular honeycomb texture on the surface; commonly found in limestone deposits worldwide.

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Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

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Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

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Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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

Porous limestone pebble

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

sedimentary
Weathered fossil bone fragment (identification uncertain) (Fossilized bone; exact taxon and mineral composition cannot be determined from the image) — fossil

Weathered fossil bone fragment (identification uncertain)

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

fossil