sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale), Color: Cream/Tan/Light Gray, Luster: Dull/Earthy, Crystal Structure: Trigonal (microcrystalline), Cleavage: Perfect rhombohedral in calcite, but usually massive.

Identified July 10, 2026More sedimentary →

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Physical properties

Hardness: 3 (Mohs scale), Color: Cream/Tan/Light Gray, Luster: Dull/Earthy, Crystal Structure: Trigonal (microcrystalline), Cleavage: Perfect rhombohedral in calcite, but usually massive.

Formation & geological history

Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the precipitation of calcium carbonate from lake or ocean water.

Uses & applications

Extensively used as a building material (cut stone), in the production of cement, as a soil conditioner in agriculture, and as a raw material in the chemical industry.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. Many limestone deposits contain fossils of marine organisms.

Field identification & locations

Can be identified in the field by its softness (it can be scratched by a copper coin) and its effervescence (bubbling) when it reacts with dilute hydrochloric acid or vinegar.