sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Structure: Fine-grained with potential fossil inclusions; Specific gravity: 2.3-2.7.

Hardness: 3 on Mohs scale
Color: Gray, tan, or white
Luster: Dull to earthy

Identified July 6, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Structure: Fine-grained with potential fossil inclusions; Specific gravity: 2.3-2.7.

Formation & geological history

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

Uses & applications

Primarily used in construction as aggregate, in cement production, for soil conditioning in agriculture, and as a chemical feedstock.

Geological facts

Limestone covers about 10% of the Earth's total land surface. Most caves are formed in limestone because it is easily dissolved by acidic groundwater.

Field identification & locations

Identify by its reaction to cold dilute hydrochloric acid (it will fizz). Commonly found in riverbeds, quarries, and coastal cliffs. Collectors look for fossilized remains within the matrix.