Rock Identifier
Ammonite Fossil (Ammonoidea) — fossil
fossil

Ammonite Fossil

Ammonoidea

AI-generated identification · may be incorrect

Hardness of 3.5-4 on the Mohs scale, typically brown, grey, or iridescent. Displays a distinctive planispiral shell structure with complex septal sutures.

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Physical properties

Hardness of 3.5-4 on the Mohs scale, typically brown, grey, or iridescent. Displays a distinctive planispiral shell structure with complex septal sutures.

Formation & geological history

Formed through the permineralization of ancient marine cephalopod shells in sedimentary rock layers dating from the Devonian to the Cretaceous period.

Uses & applications

Valued as a popular specimen for fossil collectors, educational displays, and utilized in decorative jewelry and lapidary art.

Geological facts

Ammonites are extinct marine molluses closely related to modern octopuses and squid, and they serve as excellent index fossils for dating rock strata.

Field identification & locations

Identifiable by their coiled, snail-like chambered shells embedded in sedimentary formations worldwide, particularly in marine shales and limestones.

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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

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