sedimentary
Limestone
Sedimentary rock composed mainly of calcium carbonate (CaCO3)
Hardness of 3 on the Mohs scale. Colors range from white, gray, yellow to brown. Luster is earthy to dull. Crystal structure is microcrystalline or granular. Cleavage is none, but it may have planes of weakness.
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Physical properties
Hardness of 3 on the Mohs scale. Colors range from white, gray, yellow to brown. Luster is earthy to dull. Crystal structure is microcrystalline or granular. Cleavage is none, but it may have planes of weakness.
Formation & geological history
Formed by the accumulation of skeletal fragments of marine organisms such as coral, algal, and molluscs, often in shallow marine environments over millions of years.
Uses & applications
Used extensively in construction as building material, aggregate for road bases, and as a chief raw material for the manufacture of quicklime, slaked lime, cement, and mortar.
Geological facts
Limestone often contains fossils of ancient marine life. Famous structures like the Great Pyramid of Giza are built largely of limestone.
Field identification & locations
Can be easily identified in the field by its effervescence (fizzing) when a weak acid like diluted hydrochloric acid or vinegar is applied due to the release of carbon dioxide.
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