sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale. Color: Varies from white, gray, yellow to brown. Luster: Earthy to dull. Crystal structure: Trigonal (as calcite). Cleavage: Perfect in three directions for constituent calcite crystals. Specific gravity: 2.7 to 2.9.

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

Identified July 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed mainly from 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 construction (as a building material and aggregate for road base), in the production of cement and lime, as a soil conditioner in agriculture, and in the manufacturing of glass and paper.

Geological facts

Limestone often contains fossils of ancient marine life. Famous geological formations like the Cliffs of Dover are composed almost entirely of chalk, a soft variety of 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 vinegar is applied due to the release of carbon dioxide gas.