sedimentary

Limestone

Sedimentary rock composed of Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs scale); Color: Gray, tan, white, or buff; Luster: Dull to earthy; Structure: Often contains visible grains or fossils; Specific Gravity: 2.5-2.7

Hardness: 3-4 (Mohs scale)
Color: Gray, tan, white, or buff
Luster: Dull to earthy

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs scale); Color: Gray, tan, white, or buff; Luster: Dull to earthy; Structure: Often contains visible grains or fossils; Specific Gravity: 2.5-2.7

Formation & geological history

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

Uses & applications

Primary source of lime for cement, used as a building stone, crushed stone for road base, and used as a soil conditioner in agriculture.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. Most caves are formed by the dissolution of limestone by acidic groundwater.

Field identification & locations

Can be identified in the field by its softness (scratched by a copper penny or steel) and its rapid effervescence (fizzing) when a drop of 10% hydrochloric acid is applied.