sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Grey, beige, or tan; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline calcite); Cleavage: Perfect rhombohedral but usually not visible in massive forms; Specific Gravity: 2.5-2.7

Hardness: 3 on Mohs scale
Color: Grey, beige, or tan
Luster: Dull to earthy

Identified May 14, 2026More sedimentary →

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Physical properties

Formation & geological history

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

Uses & applications

Used extensively in construction as road base, aggregate for concrete, and as a raw material for cement and lime production. Highly valued for architectural facades and decorative stone.

Geological facts

Limestone covers about 10% of the Earth's total land surface. It is the primary rock found in karst landscapes, which are characterized by caves and sinkholes due to the rock's solubility in acidic water.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin) and its effervescence (fizzing) when in contact with dilute hydrochloric acid or vinegar. Common in shallow marine deposits.