sedimentary
Fossiliferous Limestone with Brachiopod
Limestone (Calcium Carbonate, CaCO3) with Phylum Brachiopoda fossil
Hardness: 3-4 (matrix), Color: Tan to grey, Luster: Dull/Earthy, Structure: Fine-grained matrix with fan-shaped ribbing on fossil impression. Specific Gravity: ~2.7.
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Physical properties
Hardness: 3-4 (matrix), Color: Tan to grey, Luster: Dull/Earthy, Structure: Fine-grained matrix with fan-shaped ribbing on fossil impression. Specific Gravity: ~2.7.
Formation & geological history
Formed in shallow marine environments where calcium carbonate precipitated and buried marine organisms. Brachiopods were most abundant during the Paleozoic era (approx. 541 to 252 million years ago).
Uses & applications
Primarily used as educational and decorative specimens for collectors; limestone itself is used in cement, construction, and agriculture.
Geological facts
Brachiopods look like clams but are biologically distinct; while clams have left-right symmetry across the hinge, brachiopods have symmetry across the center of each individual shell valve.
Field identification & locations
Identified by the distinct fan-like radiating ribs and the soft, carbonate-rich matrix that bubbles when exposed to weak acid. Highly common in road cuts and limestone outcrops globally.
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