sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None visible in hand samples; Specific gravity: 2.5-2.7

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

Identified June 2, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None visible in hand samples; Specific gravity: 2.5-2.7

Formation & geological history

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

Uses & applications

Used extensively in construction (aggregate, cement), architecture, agriculture (soil treatment), and industrial manufacturing of glass and steel.

Geological facts

Limestone is the primary source of lime and makes up about 10% of the total volume of all sedimentary rocks on Earth. It is famous for containing diverse fossils.

Field identification & locations

Identify in the field by its susceptibility to react (fizz) with dilute hydrochloric acid. It is commonly found in large beds or layers in areas that were once prehistoric sea floors.