sedimentary
Limestone
Limestone (CaCO3)
Hardness of 3 on the Mohs scale, typically gray, white, or buff colored, dull to earthy luster, fine-grained to coarse-grained texture, reacts with dilute hydrochloric acid by effervescing.
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Physical properties
Hardness of 3 on the Mohs scale, typically gray, white, or buff colored, dull to earthy luster, fine-grained to coarse-grained texture, reacts with dilute hydrochloric acid by effervescing.
Formation & geological history
Formed mainly from the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera, often deposited in shallow marine environments over millions of years.
Uses & applications
Widely used in construction (as aggregate for road bases, crushed stone for concrete), manufacturing of cement, agricultural soil conditioning, and as a dimension stone.
Geological facts
Limestone often contains fossils of ancient marine life and can form spectacular karst landscapes with caves, sinkholes, and underground rivers due to its solubility in acidic water.
Field identification & locations
Easily identified by its reaction to acid (fizzing) and relatively soft nature. Found worldwide in sedimentary basins, cliffs, and quarries.
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