sedimentary

Limestone

Calcareous sedimentary rock (primarily Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs); Color: White, buff, or light gray; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline calcite); Cleavage: None (rhombohedral in calcite crystals); Specific gravity: 2.5-2.7

Hardness: 3-4 (Mohs)
Color: White, buff, or light gray
Luster: Dull to earthy

Identified April 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of shell, coral, algal, and fecal debris in marine environments, or by chemical precipitation from water. Formed across all geological eras from the Precambrian to present.

Uses & applications

Used widely as a building material, in the manufacture of cement and lime, as road base, and as a soil conditioner in agriculture.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary parent rock for caves and karst topography due to its solubility in slightly acidic water.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin) and its effervescence (bubbles) when a drop of dilute hydrochloric acid is applied. Found worldwide in ancient seabed deposits.