sedimentary
Limestone pebble
Sedimentary rock composed mainly of calcium carbonate (CaCO3)
Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, microcrystalline to granular structure, good cleavage in one direction for calcite, specific gravity around 2.7.
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Physical properties
Hardness of 3 on the Mohs scale, typically white, gray, or buff in color, dull to earthy luster, microcrystalline to granular structure, good cleavage in one direction for calcite, specific gravity around 2.7.
Formation & geological history
Formed through the accumulation, compaction, and cementation of organic remains such as shells, coral, and algal debris, or through chemical precipitation of calcium carbonate from water in marine environments, often millions of years old.
Uses & applications
Used extensively in construction (as aggregate for concrete, road base, and building stone), manufacturing of cement, agricultural soil conditioning, and metallurgical flux.
Geological facts
Limestone frequently contains fossils of ancient marine organisms and can dissolve slightly in acidic water, leading to the formation of caves and karst landscapes.
Field identification & locations
Identified easily by its light color and characteristic fizz when a drop of dilute hydrochloric acid is applied, due to the release of carbon dioxide. Found worldwide in sedimentary basins and ancient sea beds.
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