sedimentary

Limestone

Sedimentary rock composed primarily of Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Tan, beige, or light grey; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (conchoidal to irregular fracture).

Hardness: 3 on Mohs scale
Color: Tan, beige, or light grey
Luster: Dull to earthy

Identified May 25, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Tan, beige, or light grey; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (conchoidal to irregular fracture).

Formation & geological history

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

Uses & applications

Extensively used in construction as an aggregate, a key ingredient in cement/concrete, a soil conditioner in agriculture, and for architectural cladding.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is most famous for forming spectacular karst landscapes, such as caves, sinkholes, and towers.

Field identification & locations

Can be identified in the field using the 'acid test'—it will effervesce (fizz) when a drop of dilute hydrochloric acid is applied. It is commonly found in areas that were once ancient sea beds.