sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Light beige, tan, gray; Luster: Dull, earthy; Texture: Fine-grained to microcrystalline; Cleavage: None (conchoidal to irregular fracture); Specific Gravity: 2.5–2.7.

Hardness: 3 on Mohs scale
Color: Light beige, tan, gray
Luster: Dull, earthy

Identified July 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily in shallow, warm marine environments through the accumulation and compaction of organic debris like shells and coral, as well as chemical precipitation of calcium carbonate over millions of years.

Uses & applications

Widely used as building material, crushed stone for road base, lime production in agriculture, cement manufacturing, and soil stabilization.

Geological facts

Limestone reacts strongly with dilute acid (effervesces), releasing carbon dioxide gas. It forms dramatic karst landscapes featuring caves, sinkholes, and underground rivers over geological time.

Field identification & locations

Can be easily identified in the field using a drop of weak acid (such as vinegar or dilute HCl) which causes it to fizz. Found globally in sedimentary basins, ancient seabed deposits, and quarry sites.