fossil

Fossilized bivalve shell fragment

Calcitic mollusk shell, commonly Bivalvia; exact genus cannot be determined from the image

AI-generated identification · may be incorrect

Composed mainly of calcium carbonate as calcite (CaCO₃); Mohs hardness about 3, white to cream, dull-to-waxy luster, layered fibrous shell structure, and no prominent cleavage. The visible symmetry and growth form suggest a weathered valve or fragment rather than a mineral crystal.

Identified August 30, 2026More fossil →

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Physical properties

Formation & geological history

Formed as a marine mollusk shell, later buried and preserved through mineral stabilization or partial replacement; age is indeterminate without locality and matrix. Such fossils range from Paleozoic to Recent geological deposits.

Uses & applications

Primarily a teaching, collecting, and decorative specimen; fossil shell material may be used for calcium-carbonate products, though this small piece has no industrial value.

Geological facts

Shell fossils often retain growth lines, ribs, hinge features, or muscle-scar impressions; erosion can remove these diagnostic details and make identification uncertain.

Field identification & locations

Look for concentric growth lines, bilateral shell symmetry, a hinge or umbo, and a chalky acid reaction—dilute hydrochloric acid will fizz on calcite. Common in marine limestone, beach deposits, and sedimentary exposures.