sedimentary

Limestone

Sedimentary rock composed mainly of calcite (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale. Color: Usually white, gray, yellow, or tan. Luster: Earthy to dull. Crystal structure: Microcrystalline or fine-grained. Cleavage: None (fractures unevenly). Specific gravity: 2.7.

Hardness: 3 on Mohs scale
Color: Usually white, gray, yellow, or tan
Luster: Earthy to dull

Identified July 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of organic debris such as shells, coral, and algal debris in shallow marine environments, or through the chemical precipitation of calcium carbonate from water.

Uses & applications

Extensively used in construction as building material, crushed stone for road base, an ingredient in concrete, and in agriculture for neutralizing soil acidity.

Geological facts

Limestone often contains fossils of ancient marine organisms since it forms from ocean sediment over millions of years. Famous structures like the Great Pyramids of Giza are built largely from limestone.

Field identification & locations

Can be easily identified in the field by applying a drop of dilute hydrochloric acid, which will cause it to fizz and effervesce due to the release of carbon dioxide.