sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on the Mohs scale; Color: Varies from white, gray, yellow, to brown; Luster: Earthy to dull; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

Hardness: 3 on the Mohs scale
Color: Varies from white, gray, yellow, to brown
Luster: Earthy to dull

Identified August 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily from the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, often deposited in shallow marine environments over millions of years.

Uses & applications

Widely used in the construction industry as building stone and as a primary raw material for the manufacture of Portland cement, agricultural lime, and crushed stone for road bases.

Geological facts

Limestone often contains fossils of ancient sea life, providing crucial clues to Earth's paleoclimates and history. Famous structures like the Great Pyramids of Giza were constructed largely from limestone blocks.

Field identification & locations

Easily identified by its characteristic fizz or effervescence when a drop of weak hydrochloric acid or vinegar is applied due to the release of carbon dioxide. Found globally in sedimentary basins.