sedimentary

Fossiliferous Limestone

Biogenic Sedimentary Rock (CaCO3)

Hardness: 3 on the Mohs scale. Color: Gray, tan, or weathered white. Luster: Dull to earthy. Crystal structure: Microcrystalline calcite (hexagonal-rhombohedral). Cleavage: Perfect rhombohedral in calcite crystals. Specific gravity: 2.7 to 2.9.

Hardness: 3 on the Mohs scale
Color: Gray, tan, or weathered white
Luster: Dull to earthy

Identified July 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the accumulation and compaction of organic carbonate debris, such as shells, coral, and algal remains, typically in shallow, warm marine environments over millions of years.

Uses & applications

Used in construction, production of cement and lime, road aggregate, and as a popular educational specimen for fossil collecting.

Geological facts

Limestone often preserves exquisite details of ancient marine life, acting as a historical archive of Earth's shallow-water ecosystems from various geological periods.

Field identification & locations

Can be identified in the field by its reaction to dilute hydrochloric acid (fizzing due to calcium carbonate) and visible fossil fragments embedded in the matrix. Common worldwide.

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