sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Grey, white, or tan; Luster: Dull to earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

Hardness: 3 on Mohs scale
Color: Grey, white, or tan
Luster: Dull to earthy

Identified June 24, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Grey, white, or tan; Luster: Dull to earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

Formation & geological history

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

Uses & applications

Extensively used in construction as an aggregate for road bases, a primary ingredient in cement, and as a dimension stone for buildings. Also used in agriculture for soil conditioning.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary source of lime for the steel and chemical industries.

Field identification & locations

Can be identified in the field by its effervescence (fizzing) when coming into contact with dilute hydrochloric acid. It often contains visible fossils of ancient marine life.