Rock Identifier
Ammonite fossil (possibly polished or carved) (Ammonoidea; shell commonly preserved as calcite, aragonite, or mineral infill) — fossil
fossil

Ammonite fossil (possibly polished or carved)

Ammonoidea; shell commonly preserved as calcite, aragonite, or mineral infill

AI-generated identification · may be incorrect

The image shows a dark, flower-shaped piece with a radial chamber pattern resembling an ammonite cross-section. Ammonite shell material is typically Mohs 3–4 if calcitic (aragonite is about 3.5–4), with a coiled, chambered structure; the dark exterior may be matrix or a coating.

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Physical properties

The image shows a dark, flower-shaped piece with a radial chamber pattern resembling an ammonite cross-section. Ammonite shell material is typically Mohs 3–4 if calcitic (aragonite is about 3.5–4), with a coiled, chambered structure; the dark exterior may be matrix or a coating.

Formation & geological history

Ammonites were marine cephalopods that lived from the Devonian to the end-Cretaceous, about 400–66 million years ago. Their shells were buried in seafloor sediments and fossilized through mineral replacement or infilling.

Uses & applications

Fossils are collected, displayed, and sometimes fashioned into jewelry or decorative objects.

Geological facts

The radiating divisions are likely internal chambers; ammonite shells were divided by walls called septa.

Field identification & locations

Identify by a coiled shell and repeated chamber partitions; common fossil regions include Morocco, Madagascar, and parts of Europe and North America. The photo alone cannot confirm whether this is an ammonite or a carved substitute.

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