sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness of 3 on the Mohs scale, color ranges from white, gray, yellow to brown, dull to earthy luster, fine-grained to coarse-grained texture, excellent cleavage in rhombohedral directions for calcite.
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Physical properties
Hardness of 3 on the Mohs scale, color ranges from white, gray, yellow to brown, dull to earthy luster, fine-grained to coarse-grained texture, excellent cleavage in rhombohedral directions for calcite.
Formation & geological history
Formed primarily from the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, as well as chemical precipitation of calcium carbonate from water in shallow marine environments over millions of years.
Uses & applications
Used heavily in construction (as a building material and component of concrete and cement), agriculture (soil conditioning), and manufacturing of glass and paper.
Geological facts
Limestone often contains well-preserved fossils of ancient marine life. Famous architectural structures like the Great Pyramids of Giza and the Empire State Building utilize significant amounts of limestone.
Field identification & locations
Readily reacts and effervesces (fizzes) when a drop of weak hydrochloric acid is applied due to the presence of calcium carbonate. Common worldwide in sedimentary basins.
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