Sedimentary

Limestone

Limestone (Calcium Carbonate, CaCO3)

Hardness: 3-4 on Mohs scale. Color: Highly variable, often gray, tan, white, or brown. Luster: Dull to earthy. Structure: Commonly massive, can be crystalline or clastic. Specific Gravity: 2.5-2.7.

Hardness: 3-4 on Mohs scale
Color: Highly variable, often gray, tan, white, or brown
Luster: Dull to earthy

Identified May 31, 2026More sedimentary →

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Physical properties

Hardness: 3-4 on Mohs scale. Color: Highly variable, often gray, tan, white, or brown. Luster: Dull to earthy. Structure: Commonly massive, can be crystalline or clastic. Specific Gravity: 2.5-2.7.

Formation & geological history

Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris, or by chemical precipitation from water.

Uses & applications

Majorly used in construction as building material, aggregate for concrete, and raw material for cement. Also used in agriculture to neutralize soil acidity.

Geological facts

Limestone is very soluble in mildly acidic rain water, leading to karst topographies, including caves and sinkholes.

Field identification & locations

Identified by its relatively soft nature (can be scratched by a nail) and its effervescence (fizzing) when dilute hydrochloric acid is applied. Commonly found worldwide in sedimentary basins.