sedimentary

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: white, cream, or light grey; Luster: dull to earthy; Structure: fine-grained, clastic or non-clastic; Cleavage: none (conchoidal or irregular fracture)

Hardness: 3 on Mohs scale
Color: white, cream, or light grey
Luster: dull to earthy

Identified May 22, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: white, cream, or light grey; Luster: dull to earthy; Structure: fine-grained, clastic or non-clastic; Cleavage: none (conchoidal or irregular fracture)

Formation & geological history

Formed primarily from the accumulation of shell, coral, algal, and fecal debris in marine environments. It can also form through the precipitation of calcium carbonate from lake or ocean water. Most specimens date from the Paleozoic to Cenozoic eras.

Uses & applications

Extensively used in construction as an aggregate, cement production, glass making, and as a soil conditioner in agriculture. Pure forms are used in the chemical industry.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is the primary material found in many of the world's most famous caves and karst landscapes.

Field identification & locations

Identified in the field by its softness (can be scratched by a copper coin) and its effervescence (fizzing) when in contact with dilute hydrochloric acid. Commonly found in quarries and road cuts globally.