sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, fine-grained to coarse crystal structure, good cleavage in three directions, specific gravity of 2.71.

Identified July 31, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, fine-grained to coarse crystal structure, good cleavage in three directions, specific gravity of 2.71.

Formation & geological history

Formed through the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, typically in shallow, warm marine waters over millions of years.

Uses & applications

Widely used in the construction industry as building stone and as an aggregate for roads, in the production of cement, and in agriculture for neutralizing acidic soils.

Geological facts

Limestone often contains fossils of ancient marine life and can dissolve slightly in acidic water, creating caves and karst landscapes over long periods.

Field identification & locations

Can be identified in the field by its characteristic reaction to dilute hydrochloric acid, producing effervescence (bubbling) due to the release of carbon dioxide.