sedimentary
Crushed Limestone
Calcite-rich Sedimentary Rock (CaCO3)
Hardness: 3-4 (Mohs scale), Color: light grey to blue-grey, Luster: dull to earthy, Crystal Structure: trigonal (microcrystalline), Cleavage: rhombohedral (not visible in crushed form), Specific Gravity: 2.7
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Physical properties
Hardness: 3-4 (Mohs scale), Color: light grey to blue-grey, Luster: dull to earthy, Crystal Structure: trigonal (microcrystalline), Cleavage: rhombohedral (not visible in crushed form), Specific Gravity: 2.7
Formation & geological history
Formed through the accumulation of shell, coral, algal, and fecal debris in clear, warm, shallow marine waters. Can also form organically through the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Mostly used in construction for road base, railroad ballast, asphalt aggregate, concrete mix, and driveways. Also used in soil neutralization and cement manufacturing.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary source of lime, which is used in steel manufacturing and water treatment.
Field identification & locations
Identify in the field by its grey color and tendency to react (fizz) with dilute hydrochloric acid. It is commonly found in quarries worldwide. Collectors look for fossils often embedded within it.
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