sedimentary
Ammonite Fossil
Ammonitida (Extinct subclass of Cephalopoda)
Hardness: 3.5-4 (if calcified), Color: Grey, earthy, or brown, Luster: Dull to sub-metallic, Structure: Spiral chambered shell with suture lines
- Hardness
- 3
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Physical properties
Hardness: 3.5-4 (if calcified), Color: Grey, earthy, or brown, Luster: Dull to sub-metallic, Structure: Spiral chambered shell with suture lines
Formation & geological history
Formed through permineralization or replacement within sedimentary layers (limestone/shale). Lived during the Devonian period through the Cretaceous (66-400 million years ago).
Uses & applications
Used primarily for educational study, amateur fossil collecting, and occasionally in jewelry as polished stones or pendants.
Geological facts
Ammonites are more closely related to modern octopuses and squids than to the nautilus they resemble. Their extinction coincided with the dinosaurs.
Field identification & locations
Identify by its distinct spiral shape and ribbed texture. Commonly found in sedimentary basins, coastal cliffs, or riverbeds containing marine shale or limestone.
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