Rock Identifier
Fossilized oyster shell in limestone (Bivalvia fossil; chiefly calcite (CaCO₃)) — fossil
fossil

Fossilized oyster shell in limestone

Bivalvia fossil; chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Cream to gray, pearly-to-dull luster, layered shell growth lines and possible hinge/rib structures in a fine carbonate matrix; calcite hardness is 3 and it effervesces strongly in dilute hydrochloric acid.

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Physical properties

Cream to gray, pearly-to-dull luster, layered shell growth lines and possible hinge/rib structures in a fine carbonate matrix; calcite hardness is 3 and it effervesces strongly in dilute hydrochloric acid.

Formation & geological history

A marine bivalve shell was buried in carbonate sediment and mineralogically preserved, commonly during the Mesozoic or Cenozoic; exact age cannot be determined from the image.

Uses & applications

Primarily a collectible, educational, and decorative specimen; fossiliferous limestone may also be used as aggregate or cement raw material, though this piece is not industrial grade.

Geological facts

The shell is likely composed of original or recrystallized calcite, and its curved layered form is characteristic of oyster-like bivalves rather than a crystalline mineral.

Field identification & locations

Identify by visible shell growth layers, bilateral shell architecture, and carbonate matrix; common in marine limestone exposures worldwide, especially coastal and shallow-sea deposits.

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