sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, fine-grained to coarse crystal structure, with good cleavage in three directions (rhombohedral).

Identified August 6, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, fine-grained to coarse crystal structure, with good cleavage in three directions (rhombohedral).

Formation & geological history

Formed by the accumulation of organic remains such as shells and coral, or through the chemical precipitation of calcium carbonate from water in marine environments.

Uses & applications

Extensively used in construction (as a building material and a main component of concrete and cement), agriculture (to neutralize acidic soils), and in the manufacture of glass and paper.

Geological facts

Limestone often contains fossils of ancient marine organisms and is the primary rock type that forms caves and karst topography through dissolution by slightly acidic groundwater.

Field identification & locations

Can be easily identified in the field by its characteristic effervescence (fizzing) when a drop of dilute hydrochloric acid is applied to its surface.