sedimentary

Limestone

Sedimentary Rock (Primarily Calcium Carbonate, CaCO3)

Hardness: 3 on Mohs scale. Color: White, gray, tan, yellow, or brown. Luster: Dull to earthy. Crystal structure: Microcrystalline or fine-grained. Cleavage: None (has a conchoidal to uneven fracture). Specific gravity: 2.7 to 2.9.

Hardness: 3 on Mohs scale
Color: White, gray, tan, yellow, or brown
Luster: Dull to earthy

Identified July 30, 2026More sedimentary →

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Physical properties

Formation & geological history

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

Uses & applications

Widely used in the construction industry for crushed stone in road base, as a primary component in the manufacture of Portland cement, as agricultural lime for soil conditioning, and as a building dimension stone.

Geological facts

Limestone often contains well-preserved fossils of ancient marine organisms due to its aquatic origin. Famous structures like the Great Pyramids of Giza were partially constructed using limestone blocks.

Field identification & locations

Can be easily identified in the field by its characteristic reaction to dilute hydrochloric acid, producing visible effervescence (fizzing) as carbon dioxide gas is released. Found globally in sedimentary basins and ancient sea beds.

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Fossiliferous Concretion

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Generic Pebble / Rock Fragment

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Banded Siltstone / Mudstone Pebble

Siltstone / Argillite

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Sedimentary Sandstone

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