sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale), Color: Gray to light tan, Luster: Dull to earthy, Crystal Structure: Hexagonal (Scalenohedral) as Calcite, Cleavage: Perfect rhombohedral

Identified June 28, 2026More sedimentary →

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Physical properties

Hardness: 3 (Mohs scale), Color: Gray to light tan, Luster: Dull to earthy, Crystal Structure: Hexagonal (Scalenohedral) as Calcite, Cleavage: Perfect rhombohedral

Formation & geological history

Formed primarily in shallow marine waters by the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from lake or ocean water.

Uses & applications

Extensively used in construction as an aggregate for concrete and asphalt, used in the manufacture of cement, and as a flux in steel production.

Geological facts

Limestone is the primary source of lime and makes up about 10% of the total volume of all sedimentary rocks. It is essential for the formation of cave systems and karst topography.

Field identification & locations

Can be identified in the field by its reaction to dilute hydrochloric acid (it fizzes). Common in regions that were once ancient sea beds. Check for fossil inclusions.