sedimentary
Limestone
Calcite rock (CaCO3)
Hardness: 3 on the Mohs scale, Color: White, gray, tan, or yellowish, Luster: Dull to earthy, Crystal structure: Microcrystalline or fine-grained, Cleavage: None distinct in rock form, Specific gravity: 2.7
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Physical properties
Hardness: 3 on the Mohs scale, Color: White, gray, tan, or yellowish, Luster: Dull to earthy, Crystal structure: Microcrystalline or fine-grained, Cleavage: None distinct in rock form, Specific gravity: 2.7
Formation & geological history
Formed by the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, or through the chemical precipitation of calcium carbonate from water.
Uses & applications
Widely used in construction as building material, an aggregate for the base of roads, as an ingredient in concrete, and in the manufacturing of cement, lime, and paper.
Geological facts
Limestone often contains fossils of ancient marine life, reflecting the environmental conditions of prehistoric shallow seas.
Field identification & locations
Can be identified in the field by its characteristic effervescence (fizzing) when a drop of dilute hydrochloric acid is applied due to the presence of calcium carbonate.
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