sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, colors range from white and gray to yellow and brown, dull to earthy luster, fine-grained to coarse crystal structure, excellent cleavage in three directions (rhombohedral), specific gravity around 2.7.

Identified August 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and compaction of organic remains such as shells, coral, and algal debris, or through the chemical precipitation of calcium carbonate from water, typically in marine environments over millions of years.

Uses & applications

Extensively used in construction as a building material, a primary component in the manufacture of Portland cement, crushed stone for road base, agricultural lime to neutralize acidic soils, and in the production of glass and paper.

Geological facts

Limestone often contains fossils of ancient marine organisms, providing valuable insights into Earth's history and past environments. Famous landmarks like the Great Pyramid of Giza and the Parthenon are constructed primarily of limestone.

Field identification & locations

Can be easily identified in the field by its characteristic effervescence (fizzing) when a drop of weak hydrochloric acid or vinegar is applied due to the release of carbon dioxide gas. Found worldwide in sedimentary basins and ancient sea beds.