sedimentary

Fossiliferous Limestone with Brachiopod

Phylum Brachiopoda in calcitic matrix

AI-generated identification · may be incorrect

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

Identified May 7, 2026More sedimentary →

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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.