sedimentary
Bivalve Fossil (Clam/Mollusk)
Class: Bivalvia (Order: Veneroida), Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale), Color: Cream/Tan to Dull White, Luster: Dull/Earthy (can be pearly if aragonite is preserved), Structure: Ribbed concentric growth lines, Cleavage: None (conchoidal fracture on shell material), Specific Gravity: 2.7
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Physical properties
Hardness: 3 (Mohs scale), Color: Cream/Tan to Dull White, Luster: Dull/Earthy (can be pearly if aragonite is preserved), Structure: Ribbed concentric growth lines, Cleavage: None (conchoidal fracture on shell material), Specific Gravity: 2.7
Formation & geological history
Formed by biological precipitation of calcium carbonate in marine or freshwater environments. Petrified through permineralization or replacement within sedimentary layers. Geologically ranging from the Cambrian period to the Holocene.
Uses & applications
Paleontological study, educational tools, local craft jewelry, and inexpensive fossil collecting.
Geological facts
Bivalves are one of the most common fossils found worldwide. They have two hinged shells (valves) and have survived through several mass extinction events, making them excellent indicators for dating the age of sedimentary rock layers.
Field identification & locations
Identify by looking for symmetrical 'D' or kidney-shaped outlines with visible concentric growth ridges. Commonly found in limestone, shale, and sandstone outcrops near former sea beds or riverbanks.
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