Rock Identifier
Fossil shell fragment (Likely a fossilized brachiopod or bivalve; exact taxon cannot be determined from the image) — fossil
fossil

Fossil shell fragment

Likely a fossilized brachiopod or bivalve; exact taxon cannot be determined from the image

AI-generated identification · may be incorrect

Pale blue-gray, ribbed shell with a dull to slightly waxy luster; commonly composed of recrystallized calcite. Mohs hardness is about 3, with brittle cleavage or fracture and moderate density (~2.7 g/cm³).

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Physical properties

Pale blue-gray, ribbed shell with a dull to slightly waxy luster; commonly composed of recrystallized calcite. Mohs hardness is about 3, with brittle cleavage or fracture and moderate density (~2.7 g/cm³).

Formation & geological history

A marine shell was buried in sediment and mineralized or recrystallized during diagenesis, often preserving the original ribs and growth lines. Age is indeterminate but could range from Paleozoic to Cenozoic.

Uses & applications

Primarily a teaching, collecting, and display specimen; fossilized shell material has little industrial or jewelry use unless exceptionally attractive or polished.

Geological facts

The prominent ribs and curved valve suggest a brachiopod or ribbed bivalve. Blue coloration may reflect mineral replacement, weathering, or surface treatment rather than original shell color.

Field identification & locations

Look for bilateral shell symmetry, hinge structures, growth lines, and ribs; brachiopods are typically symmetric across each valve, whereas bivalves are symmetric between valves. Common in marine limestone and shale deposits worldwide.

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Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

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Fossilized bone; exact taxon and mineral composition cannot be determined from the image

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