sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on the Mohs scale, Color: Varies from white, gray, yellow, to brown, Luster: Dull to earthy, Crystal structure: Trigonal (calcite), Cleavage: Perfect rhombohedral cleavage, Specific Gravity: 2.71
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Physical properties
Hardness: 3 on the Mohs scale, Color: Varies from white, gray, yellow, to brown, Luster: Dull to earthy, Crystal structure: Trigonal (calcite), Cleavage: Perfect rhombohedral cleavage, Specific Gravity: 2.71
Formation & geological history
Formed in shallow marine environments through the accumulation of shell, coral, algal, and fecal debris, often over millions of years.
Uses & applications
Extensively used in construction (as building material and aggregate in road construction), cement production, agriculture (soil conditioning), and metallurgical flux.
Geological facts
Limestone often contains fossils of ancient marine organisms and can dissolve slightly in acidic water, creating caves and karst topography.
Field identification & locations
Identified easily by its reaction with dilute hydrochloric acid (fizzing/effervescence). Found worldwide in sedimentary basins and ancient sea beds.
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