sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: white to light grey; Luster: dull to earthy; Structure: non-crystalline to massive; Cleavage: none; Specific Gravity: 2.5-2.7

Hardness: 3 on Mohs scale
Color: white to light grey
Luster: dull to earthy

Identified June 1, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: white to light grey; Luster: dull to earthy; Structure: non-crystalline to massive; Cleavage: none; Specific Gravity: 2.5-2.7

Formation & geological history

Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the precipitation of calcium carbonate from lake or ocean water.

Uses & applications

Extensively used in construction as an aggregate, a key ingredient in cement, a soil conditioner in agriculture, and as a filler in products like toothpaste and paper.

Geological facts

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

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin) and its effervescence (bubbling) when touched with a weak acid like vinegar. Found globally in ancient seabed regions.