Limestone

Physical Properties

Hardness: 3 (Mohs scale), Color: light grey to dark grey, Luster: dull to earthy, Crystal structure: microcrystalline, Cleavage: usually massive, Specific gravity: 2.5-2.7

Formation & Geological History

Formed from marine deposits, often containing shells, coral, and algal debris. Geological age varies widely from Precambrian to current times. Primarily formed in shallow, calm, warm marine waters.

Uses & Applications

A major component in the production of cement, crushed stone for road bases, architectural applications, and agricultural lime to neutralize soil acidity.

Geological Facts

Limestone covers about 10% of the Earth's land surface. It is highly soluble in water, leading to the formation of extensive cave systems through karst topography.

Field Identification & Locations

Can be identified in the field by its reaction to dilute hydrochloric acid (it will fizz or effervesce). Common worldwide, often found forming prominent cliffs or exposed in river valleys.

Identified on: 4/26/2026

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