sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, colors range from white and gray to tan and brown, dull to earthy luster, fine-grained to microcrystalline structure, poor to distinct cleavage.

Identified July 31, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, colors range from white and gray to tan and brown, dull to earthy luster, fine-grained to microcrystalline structure, poor to distinct cleavage.

Formation & geological history

Formed mainly through the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, or by the chemical precipitation of calcium carbonate from water in marine and freshwater environments.

Uses & applications

Extensively used in construction as a building material, an aggregate for roads, a component of concrete, and in the manufacture of cement, agriculture lime, and various chemical products.

Geological facts

Limestone formations often host spectacular cave systems with stalactites and stalagmites due to the dissolution of calcium carbonate by acidic groundwater over thousands of years.

Field identification & locations

Can be easily identified in the field by its characteristic fizzing or effervescence when a drop of weak hydrochloric acid or white vinegar is applied to its surface.