Rock Identifier
Polished ammonite fossil (Ammonite, an extinct cephalopod; commonly polished specimens are from Jurassic or Cretaceous forms) — fossil
fossil

Polished ammonite fossil

Ammonite, an extinct cephalopod; commonly polished specimens are from Jurassic or Cretaceous forms

AI-generated identification · may be incorrect

Coiled shell with visible whorls and growth lines; typically calcite or aragonite replaced by calcite, Mohs hardness about 3–4, with a polished lustrous surface. The dark reddish-brown appearance may reflect mineral staining or treatment.

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Physical properties

Coiled shell with visible whorls and growth lines; typically calcite or aragonite replaced by calcite, Mohs hardness about 3–4, with a polished lustrous surface. The dark reddish-brown appearance may reflect mineral staining or treatment.

Formation & geological history

Ammonites lived in marine environments and their shells were buried in sediment, then fossilized through mineral replacement. The image alone does not establish the specimen’s geological age or exact species.

Uses & applications

Collected and displayed as a fossil; cut or polished ammonites are also used in jewelry and decorative objects.

Geological facts

Ammonites are extinct marine mollusks related to modern squid and nautiluses; their coiled shells are divided internally into chambers.

Field identification & locations

Look for a naturally coiled, chambered shell and repeated whorls; polishing can obscure details, and the image does not confirm authenticity or provenance. Fossils occur worldwide in marine sedimentary rocks.

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