sedimentary

Limestone

Calcium carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness of 3 on the Mohs scale, typically white, gray, or tan in color, dull to sub-earthy luster, fine-grained to coarse crystal structure, exhibits good cleavage in three directions (rhombohedral), and specific gravity ranging from 2.7 to 2.9.

Identified August 4, 2026More sedimentary →

Explore Limestone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the accumulation of organic remains such as shells, coral, and algal debris, or through the chemical precipitation of calcium carbonate from water in shallow marine environments over millions of years.

Uses & applications

Widely used in the manufacturing of cement and lime, as a building material, crushed stone for road base, agricultural soil treatment, and in the production of glass and steel.

Geological facts

Limestone often contains well-preserved fossils of ancient marine organisms and is susceptible to dissolution by acidic water, creating fascinating cave systems and karst topography.

Field identification & locations

Easily identifiable in the field by its characteristic effervescence (fizzing) when a drop of weak hydrochloric acid or vinegar is applied to its surface. Commonly found in sedimentary basins worldwide.