fossil

Bivalve Fossil (Clam Shell)

Class Bivalvia

Hardness: 3.5 to 4 on the Mohs scale (for aragonite/calcite shells); Color: White to off-white with brown or tan weathering; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic (aragonite) or Trigonal (calcite); Specific Gravity: 2.7 to 2.9.

Hardness: 3
Color: White to off-white with brown or tan weathering
Luster: Vitreous to pearly

Identified August 3, 2026More fossil →

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Physical properties

Formation & geological history

Formed through the fossilization (permineralization or replacement) of ancient marine mollusk shells, typically dating from the Paleozoic to Cenozoic eras in marine sedimentary environments.

Uses & applications

Used in paleontology research, educational displays, decorative items, and fossil collecting.

Geological facts

Bivalves first appeared during the Cambrian period over 500 million years ago and include clams, oysters, and mussels.

Field identification & locations

Found worldwide in sedimentary rock formations, especially marine limestone, shales, and ancient beach deposits. Look for impressions or preserved calcareous shell structures embedded in sedimentary layers.