sedimentary
Fossilized Brachiopod
Articulata (Class) / Brachiopoda (Phylum)
Hardness: 3-4 (calcite), Color: Tan to brown, Luster: Dull to waxy, Crystal Structure: Microcrystalline calcite replacing biological shell, Cleavage: None (conchoidal fracture when broken), Specific Gravity: 2.7
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Physical properties
Hardness: 3-4 (calcite), Color: Tan to brown, Luster: Dull to waxy, Crystal Structure: Microcrystalline calcite replacing biological shell, Cleavage: None (conchoidal fracture when broken), Specific Gravity: 2.7
Formation & geological history
Formed via permineralization or recrystallization of marine shell life. These organisms dominated Paleozoic oceans (541 to 252 million years ago) and were buried in marine sediment that eventually turned into limestone or shale.
Uses & applications
Paleontological research, educational specimens, jewelry (beads or pendants), and private collections.
Geological facts
Brachiopods are often called 'lamp shells' because they resemble ancient oil lamps. Although they look like clams, they are biologically distinct and belong to their own phylum.
Field identification & locations
Identify by symmetrical shell halves and ridged growth lines. Often found in limestone outcrops, river beds, and quarries. Collectors look for complete valves and well-defined ribbing.
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