Rock Identifier
Fossilized Oyster Shell (Ostreidae (Phylum Mollusca)) — fossil
fossil

Fossilized Oyster Shell

Ostreidae (Phylum Mollusca)

AI-generated identification · may be incorrect

Hardness of 3-4 on the Mohs scale, coloration ranging from dark grey to brown with white calcium carbonate layers, dull to pearly luster, and amorphous or layered shell structure.

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Physical properties

Hardness of 3-4 on the Mohs scale, coloration ranging from dark grey to brown with white calcium carbonate layers, dull to pearly luster, and amorphous or layered shell structure.

Formation & geological history

Formed through the permineralization of ancient bivalve mollusk shells in marine sedimentary environments, typically dating from the Cretaceous period or later.

Uses & applications

Valued primarily by fossil collectors, educational displays, and as index fossils for geological dating.

Geological facts

Oyster fossils are excellent indicators of ancient sea level changes and past marine ecosystems.

Field identification & locations

Identified by its distinctive curved bivalve shape and layered calcareous texture; commonly found in limestone and clay-rich sedimentary rock formations worldwide.

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Probable fossil-bearing rock or mineral concretion (Unidentified carbonate-rich concretion with a possible fossil inclusion) — fossil

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) — fossil

Likely fossil oyster shell

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

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

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil
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
Fossil oyster shell (Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)) — fossil

Fossil oyster shell

Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)

fossil