sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, colors range from white, gray, tan, to yellow, dull to earthy luster, rhombohedral cleavage, specific gravity of 2.7.

Identified August 1, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, colors range from white, gray, tan, to yellow, dull to earthy luster, rhombohedral cleavage, specific gravity of 2.7.

Formation & geological history

Formed through the accumulation of skeletal fragments from marine organisms like coral, mollusks, and foraminifera, or by chemical precipitation from water, typically in shallow marine environments over millions of years.

Uses & applications

Widely used in construction as building stone, a primary component of Portland cement, crushed stone for road bases, agricultural soil conditioning, and in the production of lime and glass.

Geological facts

Limestone often contains fossils of ancient sea life. Famous structures like the Great Pyramids of Giza and parts of the Empire State Building utilize limestone.

Field identification & locations

Identified by its characteristic reaction to dilute hydrochloric acid, producing effervescence (fizzing). Found worldwide in sedimentary basins, particularly in regions that were once ancient shallow seas.