Rock Identifier
Ammonite Fossil in Matrix (Ammonoidea subclass (e.g., Arietites or similar genera)) — fossil
fossil

Ammonite Fossil in Matrix

Ammonoidea subclass (e.g., Arietites or similar genera)

Mohs hardness around 3.5 to 4 (for the calcite replacement), colors range from brown and tan to white, vitreous to dull luster, planispiral shell structure with complex septa and sutures.

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Physical properties

Mohs hardness around 3.5 to 4 (for the calcite replacement), colors range from brown and tan to white, vitreous to dull luster, planispiral shell structure with complex septa and sutures.

Formation & geological history

Formed during the Mesozoic Era (approx. 66 to 240 million years ago) when cephalopods died and settled on sea floors, eventually becoming permineralized or replaced by minerals like calcite within sedimentary rock matrices.

Uses & applications

Used in decorative art, polished paperweights, jewelry, educational specimens, and paleontology collections.

Geological facts

Ammonites are extinct marine mollusk animals closely related to modern-day nautiluses, octopuses, and squids. They are excellent index fossils used by geologists to date rock layers.

Field identification & locations

Easily identified by their characteristic coiled spiral shells embedded in stone. Commonly sourced from locations such as Madagascar, Morocco, and various limestone-rich deposits worldwide.

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