sedimentary

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Mohs hardness of 3, light tan to off-white or beige color, dull to earthy luster, soft to fine-grained texture, reacts strongly with cold dilute hydrochloric acid.

Identified July 27, 2026More sedimentary →

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Physical properties

Mohs hardness of 3, light tan to off-white or beige color, dull to earthy luster, soft to fine-grained texture, reacts strongly with cold dilute hydrochloric acid.

Formation & geological history

Formed primarily in shallow, warm marine environments through the accumulation of organic debris like shells, coral, algal fragments, and microscopic organism remains, or through chemical precipitation of calcite.

Uses & applications

Widely used in construction as crushed stone, concrete aggregate, soil conditioner, lime production, building facade stone, and cement manufacturing.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks worldwide. Caverns and karst topography are formed when acidic groundwater dissolves limestone over long periods.

Field identification & locations

Identified by its soft texture, pale color, and vigorous effervescence (fizzing) when tested with dilute acid. Commonly found in marine sedimentary basins worldwide.