sedimentary

Limestone

Calcium Carbonate (CaCO3 / Calcite)

Hardness: 3 on Mohs scale. Color: Light grey, off-white, beige. Luster: Dull to earthy. Texture: Fine-grained, microcrystalline, slightly rough to grainy.

Hardness: 3 on Mohs scale
Color: Light grey, off-white, beige
Luster: Dull to earthy

Identified July 22, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale. Color: Light grey, off-white, beige. Luster: Dull to earthy. Texture: Fine-grained, microcrystalline, slightly rough to grainy.

Formation & geological history

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

Uses & applications

Widely used in construction aggregate, cement manufacturing, soil neutralization in agriculture, chemical production, and as a dimension stone.

Geological facts

Limestone forms extensive karst landscapes around the world, creating vast cave systems and sinkholes. It reacts vigorously with dilute hydrochloric acid, producing carbon dioxide gas bubbles.

Field identification & locations

Identified in the field by its softness (can be scratched with a steel nail), dull earthy texture, light gray appearance, and effervescence (fissing) when exposed to a weak acid like vinegar.