sedimentary

Limestone

Sedimentary rock composed primarily of Calcite (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale); Color: Gray, tan, or white; Luster: Dull/Earthy; Structure: Fine-grained/Microcrystalline; Cleavage: None (has conchoidal or irregular fracture); Specific Gravity: 2.5-2.7

Hardness: 3 (Mohs scale)
Color: Gray, tan, or white
Luster: Dull/Earthy

Identified July 12, 2026More sedimentary →

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Physical properties

Hardness: 3 (Mohs scale); Color: Gray, tan, or white; Luster: Dull/Earthy; Structure: Fine-grained/Microcrystalline; Cleavage: None (has conchoidal or irregular fracture); Specific Gravity: 2.5-2.7

Formation & geological history

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

Uses & applications

Extensively used in construction as aggregate, for making cement/mortar, as a soil conditioner in agriculture, and for the production of lime.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary host for karst landscapes including caves and sinkholes.

Field identification & locations

Identifiable in the field by its softness (can be scratched by a steel nail) and its effervescence (bubbling) when a drop of dilute hydrochloric acid or vinegar is applied. Found globally in ancient seabed deposits.