sedimentary

Limestone

CaCO3 (Limestone)

Hardness: 3 (Mohs Scale), Color: Grey to creamy white, Luster: Dull to earthy, Structure: Massive/Grained, Cleavage: None (Exhibits conchoidal to irregular fracture), Specific Gravity: 2.3 to 2.7

Identified July 18, 2026More sedimentary →

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Physical properties

Hardness: 3 (Mohs Scale), Color: Grey to creamy white, Luster: Dull to earthy, Structure: Massive/Grained, Cleavage: None (Exhibits conchoidal to irregular fracture), Specific Gravity: 2.3 to 2.7

Formation & geological history

Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris. It is also created through the chemical precipitation of calcium carbonate from lake or ocean water.

Uses & applications

Primarily used in construction as aggregate, cement manufacture, building stone, and in agriculture as soil conditioner (lime).

Geological facts

Limestone is the primary component of most cave systems and is essential for the production of glass and steel. It often contains fossils of ancient sea life.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin) and its lively effervescence when exposed to a 10% solution of hydrochloric acid.