sedimentary
Limestone
Calcite (CaCO3)
Hardness of 3 on the Mohs scale, light grey to brownish grey in color, dull to sub-vitreous luster, microcrystalline sedimentary structure, effervesces vigorously in diluted acid.
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Physical properties
Hardness of 3 on the Mohs scale, light grey to brownish grey in color, dull to sub-vitreous luster, microcrystalline sedimentary structure, effervesces vigorously in diluted acid.
Formation & geological history
Formed in shallow, warm marine waters through the accumulation and compaction of shell, coral, algal, and fecal debris, or chemical precipitation of calcium carbonate.
Uses & applications
Extensively used as a building material, aggregate for concrete, raw material for cement manufacture, soil conditioner in agriculture, and chemical feedstock.
Geological facts
Limestone constitutes about 10% of the total volume of all sedimentary rocks. Famous geological features like the White Cliffs of Dover and extensive karst cave systems are composed of limestone.
Field identification & locations
Can be identified in the field by its softness (scratched by a copper penny or steel blade) and reaction with acid. Abundant worldwide in ancient marine basins.
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