sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness of 3 on the Mohs scale, typically white, gray, or buff-colored with an earthy to vitreous luster. It features a fine-grained to coarse crystal structure and reacts vigorously with dilute hydrochloric acid.

Identified October 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of organic debris like shell, coral, and algal fragments, or via chemical precipitation in shallow marine environments over millions of years.

Uses & applications

Widely used in the manufacture of Portland cement, as crushed stone for road base, agricultural soil conditioning, and dimensional building stone.

Geological facts

Limestone frequently preserves exceptionally well-detailed fossils due to the calm marine environments where it accumulates. Famous architectural landmarks like the Great Pyramids of Giza were constructed largely from limestone.

Field identification & locations

Identify in the field by its characteristic pale color, relative softness, and immediate fizzing reaction when exposed to acid. It is globally abundant in sedimentary basins and ancient sea beds.