sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: light gray to tan; Luster: dull to earthy; Structure: microcrystalline or clastic; Cleavage: none (conchoidal fracture).

Hardness: 3 on Mohs scale
Color: light gray to tan
Luster: dull to earthy

Identified June 3, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: light gray to tan; Luster: dull to earthy; Structure: microcrystalline or clastic; Cleavage: none (conchoidal fracture).

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 lake or ocean water.

Uses & applications

Extensively used in construction as an aggregate, cement production, agriculture (soil lime), and sometimes as a building stone or for landscape design.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is used to make white pigments and fillers for products like toothpaste and paper.

Field identification & locations

Identified by its reaction to dilute hydrochloric acid (it will fizz). Often contains visible fossils and is common in regions with ancient seabed history.