fossil

Bivalve Fossil (Clam)

Class Bivalvia (e.g., Mercenaria or similar genus), composed of CaCO3 (Aragonite/Calcite)

Hardness: 3-4 (Mohs scale); Color: Chalky white to cream; Luster: Dull, earthy; Structure: Planar concentric growth lines with a distinct umbo (beak); Shape: Oval to sub-circular shell valves.

Hardness: 3-4 (Mohs scale)
Color: Chalky white to cream
Luster: Dull, earthy

Identified July 7, 2026More fossil →

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Physical properties

Hardness: 3-4 (Mohs scale); Color: Chalky white to cream; Luster: Dull, earthy; Structure: Planar concentric growth lines with a distinct umbo (beak); Shape: Oval to sub-circular shell valves.

Formation & geological history

Formed in marine or freshwater sedimentary environments via permineralization or replacement. These fossils can range from the Cambrian period to the Holocene, commonly found in limestone or shale beds.

Uses & applications

Scientific research, educational study, and decorative collecting. In some contexts, fossiliferous limestone is used in construction.

Geological facts

Bivalves are one of the most successful groups of mollusks. Their fossils are excellent paleoenvironmental indicators, telling scientists about the water temperature and depth of ancient seas.

Field identification & locations

Identify by looking for bilateral symmetry between two halves (valves) and concentric growth rings. Common along coastal ridges, ancient seabed outcrops, and riverbeds. Fragile when weathered.

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