sedimentary
Ammonite Fossil
Ammonoidea (Calcium carbonate or Pyrite replacement)
Hardness: 3.5 - 4.0; Color: Dark grey to pearly white; Luster: Pearly to dull; Crystal structure: Planispiral shell; Cleavage: None
- Hardness
- 3
- Color
- Dark grey to pearly white
- Luster
- Pearly to dull
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Physical properties
Hardness: 3.5 - 4.0; Color: Dark grey to pearly white; Luster: Pearly to dull; Crystal structure: Planispiral shell; Cleavage: None
Formation & geological history
Formed in marine environments during the Devonian through the Cretaceous periods (approx. 400 to 66 million years ago) specifically through permineralization within sedimentary basins.
Uses & applications
Primarily used for educational collecting, decorative items, and semi-precious jewelry (Ammolite).
Geological facts
Ammonites are extinct marine mollusks related to modern squids and octopuses. They used their chambered shells to regulate buoyancy in the water column.
Field identification & locations
Identify by looking for the distinct coiled spiral shape and suture lines on the surface. Commonly found in limestone or shale cliffs in coastal regions like Dorset, UK or Morocco.
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