sedimentary

Fossiliferous Limestone (with Oyster Fossils)

Fossiliferous Calcarenite / Bivalve Mollusk Fossil

Hardness: 3 (calcite matrix); Color: Gray-buff, tan, and cream; Luster: Dull, earthy; Crystal structure: Amorphous/microcrystalline matrix; Cleavage: None (rhombohedral in calcite crystals within shells)

Hardness: 3 (calcite matrix)
Color: Gray-buff, tan, and cream
Luster: Dull, earthy

Identified June 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow marine environments where accumulation of calcium carbonate shells occurred. These sediments were buried and lithified via chemical precipitation over millions of years, typically dating from the Cretaceous to Cenozoic eras.

Uses & applications

Used in construction as building stone, in the production of cement, for soil conditioning in agriculture, and as decorative pieces for collectors.

Geological facts

This specimen contains several fossilized oyster shells (Ostreidae). Oysters are known to form dense 'reefs' or beds which, when fossilized, provide excellent records of ancient sea levels and water temperatures.

Field identification & locations

Identify in the field by looking for layered shell fragments and reacting with dilute hydrochloric acid (it will fizz). Commonly found in sedimentary basins and coastal cliffs. Collectors should look for well-preserved hinge segments.

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