sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale); Color: White, grayish, tan; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (rhombohedral in calcite form); Specific Gravity: 2.3–2.7

Hardness: 3 (Mohs scale)
Color: White, grayish, tan
Luster: Dull to earthy

Identified June 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. Can also form through chemical precipitation from ocean or lake water.

Uses & applications

Extensively used in construction as aggregate for concrete, road base, and architectural building stone. Also vital in manufacturing cement, steel, and as a soil conditioner in agriculture.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It often contains visible fossils of marine organisms like brachiopods and crinoids.

Field identification & locations

Identify in the field by its tendency to effervesce (fizz) when in contact with dilute hydrochloric acid. Commonly found in quarries and outcrops in regions that were once ancient sea beds.