sedimentary

Limestone / Dolomite

Calcium Carbonate (CaCO3) / Calcium Magnesium Carbonate (CaMg(CO3)2)

AI-generated identification · may be incorrect

Hardness: 3-4 on Mohs scale; Color: Light gray to off-white; Luster: Dull to earthy; Texture: Fine-grained to crystalline; Specific Gravity: 2.5-2.7

Hardness: 3-4 on Mohs scale
Color: Light gray to off-white
Luster: Dull to earthy

Identified July 25, 2026More sedimentary →

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Physical properties

Hardness: 3-4 on Mohs scale; Color: Light gray to off-white; Luster: Dull to earthy; Texture: Fine-grained to crystalline; Specific Gravity: 2.5-2.7

Formation & geological history

Formed primarily in shallow, warm marine environments through the accumulation of organic debris like shells, coral, and algal remains, or chemical precipitation of calcium carbonate over millions of years.

Uses & applications

Extensively used as crushed stone for road construction, concrete aggregate, flux in steelmaking, soil acid neutralizer in agriculture, and building stone.

Geological facts

Limestone is the primary ingredient in Portland cement. Vast limestone karst landscapes around the world contain major cave systems created by water dissolving the carbonate rock.

Field identification & locations

Identified by its softness (can be scratched with a steel nail) and strong effervescence (fizzing) when exposed to dilute acid like vinegar. Commonly found in quarries, roadcuts, and riverbeds.