Rock Identifier
Polished ammonite fossil (Ammonoidea (likely a polished ammonite shell; exact species indeterminable from the image)) — fossil
fossil

Polished ammonite fossil

Ammonoidea (likely a polished ammonite shell; exact species indeterminable from the image)

AI-generated identification · may be incorrect

The coiled shell shows segmented chambers and a glossy gold, brown, and cream surface, likely polished fossil shell with decorative metal-colored coating or inlay. Original shell material is commonly calcite or aragonite; Mohs hardness varies with preservation and alteration, typically about 3–4 for calcite.

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Physical properties

The coiled shell shows segmented chambers and a glossy gold, brown, and cream surface, likely polished fossil shell with decorative metal-colored coating or inlay. Original shell material is commonly calcite or aragonite; Mohs hardness varies with preservation and alteration, typically about 3–4 for calcite.

Formation & geological history

Ammonites were marine cephalopods that lived from the Devonian to the end-Cretaceous extinction, about 400–66 million years ago. Their shells were buried in marine sediments and later fossilized; the specimen appears cut and polished.

Uses & applications

Collected as a fossil and used in jewelry or decorative objects; polished ammonites are popular display pieces.

Geological facts

Ammonite chamber walls form intricate sutures, the wavy patterns visible on many fossil shells.

Field identification & locations

Look for a coiled planispiral shell divided into chambers, often with distinctive suture lines; notable deposits occur in Madagascar, Morocco, and Alberta, Canada. The pictured gold appearance may reflect treatment, so it should not be assumed to be naturally metallic.

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