sedimentary
Limestone
Calcium Carbonate (CaCO3)
Mohs hardness 3, light brown to beige color, dull to earthy luster, microcrystalline, strong effervescence with diluted acid, specific gravity ~2.5-2.7
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Physical properties
Mohs hardness 3, light brown to beige color, dull to earthy luster, microcrystalline, strong effervescence with diluted acid, specific gravity ~2.5-2.7
Formation & geological history
Formed in shallow, warm marine environments by the accumulation and compaction of organic debris such as shell fragments, coral, and algae over millions of years.
Uses & applications
Widely used in construction as crushed stone, in the production of cement and lime, soil treatment in agriculture, and as a building stone.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. Karst landscapes, featuring caves and sinkholes, often form in limestone regions due to its solubility in acidic water.
Field identification & locations
Identified by its softness (can be scratched with a steel key or nail) and its rapid reaction (fizzing) when exposed to cold dilute hydrochloric acid or household vinegar. Extremely common worldwide.
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