Rock Identifier
Fossilized ammonite fragment (Ammonoidea; likely an ammonite suture-section specimen, commonly Jurassic–Cretaceous) — fossil
fossil

Fossilized ammonite fragment

Ammonoidea; likely an ammonite suture-section specimen, commonly Jurassic–Cretaceous

AI-generated identification · may be incorrect

Fossilized aragonite/calcite shell in brown, cream, and orange tones; typically Mohs 3–4, earthy to waxy luster, and coiled chambered structure with visible septal sutures. The bead-like repeated forms are shell chambers or suture patterns, not mineral crystals.

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Physical properties

Fossilized aragonite/calcite shell in brown, cream, and orange tones; typically Mohs 3–4, earthy to waxy luster, and coiled chambered structure with visible septal sutures. The bead-like repeated forms are shell chambers or suture patterns, not mineral crystals.

Formation & geological history

Ammonites were extinct marine cephalopods whose shells were buried in fine sediment and mineral-replaced or infilled during diagenesis, often 66–201 million years old. Common sources include Jurassic and Cretaceous marine deposits.

Uses & applications

Primarily a collectible, educational specimen, or jewelry/cabochon material; polished ammonite sections are used decoratively and occasionally marketed as gemstones.

Geological facts

Ammonite sutures became increasingly elaborate through evolution and help identify species and geological age. The specimen appears cut and polished, exposing internal chambers and sutures.

Field identification & locations

Identify by a tightly coiled shell, repeated chambers, and complex dividing lines; distinguish it from agate by its organic spiral architecture. Commonly found in Morocco, Madagascar, England, Germany, Canada, and the western United States.

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