sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale), Color: light gray to off-white, Luster: dull to earthy, Structure: massive or bedded, Cleavage: none in bulk forms, Specific Gravity: 2.5-2.7
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Physical properties
Hardness: 3 (Mohs scale), Color: light gray to off-white, Luster: dull to earthy, Structure: massive or bedded, Cleavage: none in bulk forms, Specific Gravity: 2.5-2.7
Formation & geological history
Formed primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also be formed by chemical precipitation from ocean water or groundwater.
Uses & applications
Used extensively in construction as road base, concrete aggregate, and building stone. It is also used in the production of cement and as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. Most cave systems are formed in limestone deposits via dissolution by acidic groundwater.
Field identification & locations
Identify in the field by its softness (can be scratched by a copper coin) and its effervescence (bubbling) when in contact with a weak acid like vinegar. Common in ancient seabed locations.
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