sedimentary

Fossiliferous Limestone

Biogenic Sedimentary Rock (Calcium Carbonate, CaCO3)

Hardness: 3 on the Mohs scale; Color: Brown, gray, or tan; Luster: Dull to earthy; Crystal Structure: Microcrystalline calcite matrix containing visible fossil fragments (crinoids, brachiopods, or bryozoans); Cleavage: Perfect rhombohedral in calcite crystals; Specific Gravity: 2.5 - 2.7.

Hardness: 3 on the Mohs scale
Color: Brown, gray, or tan
Luster: Dull to earthy

Identified July 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, warm marine environments where the accumulation of calcareous skeletal fragments from marine organisms consolidated and lithified over millions of years.

Uses & applications

Used in construction, production of cement, road aggregate, and dimension stone.

Geological facts

Limestone often preserves ancient marine ecosystems, and the fossil fragments visible on the surface of this specimen provide a snapshot of prehistoric biodiversity.

Field identification & locations

Readily reacts with dilute hydrochloric acid (fizzing due to release of carbon dioxide); commonly found in sedimentary basins worldwide.

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