sedimentary

Limestone

Calcareous sedimentary rock (CaCO3)

Hardness: 3 on the Mohs scale. Color: Generally light colored, gray, white, yellow, or brown. Luster: Earthy to sub-vitreous. Crystal structure: Microcrystalline to macrocrystalline calcite. Specific gravity: 2.7 to 2.9.

Hardness: 3 on the Mohs scale
Color: Generally light colored, gray, white, yellow, or brown
Luster: Earthy to sub-vitreous

Identified August 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, or through the chemical precipitation of calcium carbonate from water. Geologically ranges from Precambrian to recent times.

Uses & applications

Widely used in construction, as aggregate for road bases, as an essential component of Portland cement, in agriculture to neutralize acidic soils, and in the production of lime and glass.

Geological facts

Limestone often contains well-preserved fossils of ancient marine life. Famous architectural structures like the Great Pyramid of Giza and parts of the Empire State Building utilize limestone.

Field identification & locations

Easily identified by its reaction to dilute hydrochloric acid, which causes it to effervesce (fizz) due to the release of carbon dioxide gas. Found worldwide in sedimentary basins.