fossil
Cockle Shell (Bivalve)
Cardiidae (Calcium Carbonate, CaCO3)
Hardness: 3-3.5 (Mohs scale), Color: tan to whitish-brown, Luster: dull to pearly, Structure: fan-shaped with radiating ribs, Cleavage: none (splintery fracture)
- Hardness
- 3-3
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Physical properties
Hardness: 3-3.5 (Mohs scale), Color: tan to whitish-brown, Luster: dull to pearly, Structure: fan-shaped with radiating ribs, Cleavage: none (splintery fracture)
Formation & geological history
Produced by marine mollusks as protective exoskeletons; composed of aragonite or calcite. While this is a modern shell, they are the primary constituents of limestone and fossilize easily in sedimentary environments.
Uses & applications
Decorative collecting, calcium source in poultry feed, historic use as currency, and indicators of paleoenvironments in geology.
Geological facts
The heart-shaped profile of the two shells joined together gave them the name 'Cardiidae' from the Greek word for heart. They are close relatives of clams and oysters.
Field identification & locations
Identified by the distinct radiating ribs and symmetrical fan shape. Commonly found on beaches worldwide and within sedimentary rock strata like limestone.
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