Rock Identifier
Polished goniatite fossil limestone (Goniatite-bearing Devonian–Carboniferous limestone; fossil cephalopod shells (Goniatitida) in calcite-rich matrix) — fossil
fossil

Polished goniatite fossil limestone

Goniatite-bearing Devonian–Carboniferous limestone; fossil cephalopod shells (Goniatitida) in calcite-rich matrix

AI-generated identification · may be incorrect

Polished dark brown to black carbonate with pale, coiled shell cross-sections; calcite has Mohs hardness 3, vitreous to waxy luster, and trigonal crystal structure. Fossils and matrix are commonly calcite or aragonite replaced by calcite.

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Physical properties

Polished dark brown to black carbonate with pale, coiled shell cross-sections; calcite has Mohs hardness 3, vitreous to waxy luster, and trigonal crystal structure. Fossils and matrix are commonly calcite or aragonite replaced by calcite.

Formation & geological history

Marine sediments accumulated roughly 360–400 million years ago; buried and lithified, with cephalopod shells preserved or mineral-replaced. Common fossil-bearing deposits occur in parts of Morocco and Europe.

Uses & applications

Used as a collectible, display specimen, and polished ornamental stone; occasionally made into jewelry or small carvings.

Geological facts

Goniatites were extinct marine cephalopods related to modern nautiluses and squids; their coiled shells show chamber divisions that can appear as rings in polished cross-section.

Field identification & locations

Look for repeated coiled, chambered shell patterns embedded in a continuous limestone matrix. The polished, shaped specimen appears consistent with commercial Moroccan fossil limestone; verify provenance for precise age and locality.

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