sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale), Color: Gray to tan, Luster: Dull/Earthy, Structure: Fine-grained/Microcrystalline, Specific Gravity: 2.3-2.7
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Physical properties
Hardness: 3 (Mohs scale), Color: Gray to tan, Luster: Dull/Earthy, Structure: Fine-grained/Microcrystalline, Specific Gravity: 2.3-2.7
Formation & geological history
Formed in marine environments from the accumulation of coral, shell, algal, and fecal debris. It is often found in sedimentary basins and can range from hundreds of millions to a few thousand years old.
Uses & applications
Used primarily in construction (aggregate, cement), agriculture (soil conditioner), and industrial chemical processes.
Geological facts
Limestone is the primary source of lime used in making glass and refining sugar. Many famous caves, like Carlsbad Caverns, are formed within limestone layers.
Field identification & locations
Identify by its reaction (fizzing) when exposed to a drop of muriatic acid or strong vinegar. It is commonly found in road cuts, quarries, and coastal outcrops.
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