sedimentary

Limestone

Sedimentary Rock (Primarily CaCO3)

Hardness of 3 on the Mohs scale, typically gray, tan, or white in color, dull to earthy luster, fine-grained to coarse crystal structure, good cleavage along planes, specific gravity around 2.7.

Identified July 31, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, typically gray, tan, or white in color, dull to earthy luster, fine-grained to coarse crystal structure, good cleavage along planes, specific gravity around 2.7.

Formation & geological history

Formed in shallow marine environments through the accumulation of shell, coral, algal, and fecal debris, or via the chemical precipitation of calcium carbonate from water.

Uses & applications

Widely used in construction as building material, an aggregate for roads, a major component of cement, and in agriculture to neutralize acidic soils.

Geological facts

Limestone frequently contains fossils of ancient marine organisms and can form dramatic geological features such as caves, sinkholes, and karst topography.

Field identification & locations

Easily identified by its characteristic fizz when exposed to dilute hydrochloric acid due to the release of carbon dioxide gas. Found worldwide in sedimentary basins.