sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: typically white, gray, or tan; Luster: dull to earthy; Texture: fine-grained to clastic; Cleavage: none in bulk rock form; Reacts strongly with dilute hydrochloric acid.

Hardness: 3 on Mohs scale
Color: typically white, gray, or tan
Luster: dull to earthy

Identified June 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily in shallow marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through the chemical precipitation of calcium carbonate from lake or ocean water.

Uses & applications

Used extensively as a building material, in the manufacturing of cement/concrete, as an aggregate for road bases, and in the production of lime for agriculture.

Geological facts

Limestone accounts for about 10% of the total volume of all sedimentary rocks. It is the primary rock found in karst landscapes, leading to the formation of spectacular caves and sinkholes.

Field identification & locations

Identify in the field by its light color and by applying a small amount of vinegar or weak acid; it should fizz (effervesce). It is common in areas that were once prehistoric seafloors.