sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, colors range from white, gray, yellow to brown, luster is earthy to sub-vitreous, crystal structure is trigonal/hexagonal (calcite), cleavage is perfect in three directions, specific gravity is 2.71

Identified July 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of skeletal fragments of marine organisms like coral, algal, and foraminifera, as well as chemical precipitation of calcium carbonate from water in shallow marine environments over millions of years

Uses & applications

Widely used in construction as building material, an aggregate for the base of roads, as an ingredient in cement, in agriculture to neutralize acidic soil, and in the manufacturing of glass and paper

Geological facts

Limestone often contains fossils of ancient marine life. Famous geological formations like the White Cliffs of Dover and many cave systems (stalactites and stalagmites) are composed primarily of limestone

Field identification & locations

Can be easily identified in the field by its characteristic fizzing or effervescence when a drop of weak hydrochloric acid (or vinegar) is applied due to the release of carbon dioxide gas. Found worldwide in sedimentary basins