sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Off-white, gray, or tan; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (fractures irregularly).

Hardness: 3 on Mohs scale
Color: Off-white, gray, or tan
Luster: Dull to earthy

Identified July 14, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Off-white, gray, or tan; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (fractures irregularly).

Formation & geological history

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

Uses & applications

Extensively used in construction as an aggregate, a key component in cement production, a building stone, and in agriculture as a soil conditioner (aglime).

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. Many world-famous caves and karst landscapes are formed in thick limestone deposits through the acidity of groundwater.

Field identification & locations

Can be identified in the field by its effervescence (fizzing) when a drop of dilute hydrochloric acid is applied. Look for it in outcrop areas with visible bedding or fossil remains.