sedimentary
Fossiliferous Limestone with Brachiopod
Phylum Brachiopoda in calcitic matrix
Hardness: 3 (matrix); Color: Gray, tan, white; Luster: Dull to earthy; Structure: Biogenic sedimentary; Cleavage: None (conchoidal fracture typical of limestone)
- Hardness
- 3 (matrix)
- Color
- Gray, tan, white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (matrix); Color: Gray, tan, white; Luster: Dull to earthy; Structure: Biogenic sedimentary; Cleavage: None (conchoidal fracture typical of limestone)
Formation & geological history
Formed in shallow marine environments where shells accumulate on the ocean floor and are lithified over millions of years, often dating from the Paleozoic era.
Uses & applications
Scientific study, educational tools, and common collector items. Large deposits are used for crushed stone and lime production.
Geological facts
Brachiopods look like clams but are actually separate biologically; they have bilateral symmetry across the shell rather than between two shells.
Field identification & locations
Look for distinct rib-like 'costae' textures and a symmetrical heart or fan shape. Commonly found in limestone outcrops and riverbeds in the Midwest US and UK.
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