sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on the Mohs scale. Color: White, gray, tan, yellow, or brown. Luster: Dull to earthy. Crystal structure: Trigonal (as calcite). Cleavage: Perfect in three directions (rhombohedral). Specific gravity: 2.71.

Hardness: 3 on the Mohs scale
Color: White, gray, tan, yellow, or brown
Luster: Dull to earthy

Identified July 30, 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. Deposited in marine environments over millions of years.

Uses & applications

Widely used in the construction industry as a building material, as an aggregate for road bases, as an ingredient in concrete, and in the manufacturing of cement, lime, and steel.

Geological facts

Limestone often contains fossils of ancient sea creatures. Famous structures built with limestone include the Great Pyramid of Giza and the Empire State Building.

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.