sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: white, cream, or gray; Luster: dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific gravity: 2.7

Hardness: 3 on Mohs scale
Color: white, cream, or gray
Luster: dull to earthy

Identified May 20, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: white, cream, or gray; Luster: dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific gravity: 2.7

Formation & geological history

Formed primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from calcium-rich waters.

Uses & applications

Extensively used as a building material, aggregate for concrete, manufacture of lime and cement, and in the production of steel and glass.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary material found in many of the world's most famous caves and karst landscapes.

Field identification & locations

Can be identified in the field by its reaction to dilute hydrochloric acid (effervescence) and its relatively soft surface that can be scratched with a penny. Commonly found in former seabed locations.