sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: typically white, gray, or tan; Luster: dull to earthy; Texture: fine to coarse grained; Cleavage: none (fractures); Specific Gravity: 2.7

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

Identified May 30, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: typically white, gray, or tan; Luster: dull to earthy; Texture: fine to coarse grained; Cleavage: none (fractures); Specific Gravity: 2.7

Formation & geological history

Primarily formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from ocean water or cave environments.

Uses & applications

Used extensively in construction as building stone and aggregate, in the production of cement, for soil neutralization in agriculture, and as a filler in paper, plastics, and paint.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary rock type found in karst landscapes, which are famous for spectacular caves and sinkholes.

Field identification & locations

Identify in the field by its reaction to cold dilute hydrochloric acid (it fizzes). Often contains visible marine fossils. Commonly found in areas that were once prehistoric shallow seabeds.