sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale, Color: White, gray, yellow, or brown, Luster: Dull to earthy, Crystal structure: Trigonal (Calcite), Specific gravity: 2.71

Identified July 28, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale, Color: White, gray, yellow, or brown, Luster: Dull to earthy, Crystal structure: Trigonal (Calcite), Specific gravity: 2.71

Formation & geological history

Formed by 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

Used extensively in construction (as building blocks and aggregate in concrete), manufacture of lime and cement, agricultural soil conditioning, and metallurgy.

Geological facts

Limestone often contains fossils, providing a rich record of Earth's ancient marine life. Famous structures like the Great Pyramid of Giza are partially built from limestone.

Field identification & locations

Identified easily by its characteristic fizz when a weak acid like vinegar is applied due to the release of carbon dioxide. Found worldwide in sedimentary basins.