sedimentary
Limestone
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs); Color: Off-white, grey, tan; Luster: Dull to earthy; Structure: Microcrystalline or fossiliferous; Grain: Fine to medium grained.
- Hardness
- 3-4 (Mohs)
- Color
- Off-white, grey, tan
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (Mohs); Color: Off-white, grey, tan; Luster: Dull to earthy; Structure: Microcrystalline or fossiliferous; Grain: Fine to medium grained.
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in marine environments. It can also form through chemical precipitation from ocean or lake water.
Uses & applications
Extensively used in construction as aggregate, cement production, agriculture (to neutralize soil acidity), and as a building stone.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Most of the world's caves are formed in limestone because it is soluble in slightly acidic groundwater.
Field identification & locations
Identified in the field by its reaction (fizzing) with dilute hydrochloric acid. It is commonly found in ancient seabed locations and is often used in landscaping gravel.
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