sedimentary

Limestone

Sedimentary carbonate rock (CaCO3)

Hardness: 3 on the Mohs scale. Color: typically white, gray, tan, or yellowish. Luster: dull to earthy. Crystal structure: microcrystalline or fine-grained calcite crystals. Cleavage: rhombohedral in calcite crystals. Specific gravity: 2.7 to 2.9.

Hardness: 3 on the Mohs scale
Color: typically white, gray, tan, or yellowish
Luster: dull to earthy

Identified July 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms mainly through the accumulation of skeletal fragments of marine organisms such as coral, algae, and foraminifera, or via the chemical precipitation of calcium carbonate from water. Deposited in shallow marine environments over millions of years.

Uses & applications

Extensively 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 frequently 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

Can be easily identified in the field by its characteristic fizz or effervescence when a drop of weak hydrochloric acid or household vinegar is applied to its surface, due to the release of carbon dioxide gas.