sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs Scale), Color: Grey, Tan, or White, Luster: Dull to earthy, Cleavage: Not visible in massive form, Specific Gravity: 2.5-2.7
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Physical properties
Hardness: 3 (Mohs Scale), Color: Grey, Tan, or White, Luster: Dull to earthy, Cleavage: Not visible in massive form, Specific Gravity: 2.5-2.7
Formation & geological history
Forms primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Extensively used in construction as an aggregate, as a base for roads, in the manufacturing of cement, and as a soil conditioner in agriculture.
Geological facts
Limestone is the primary rock type found in karst landscapes, resulting in beautiful cave structures and sinkholes when dissolved by slightly acidic groundwater.
Field identification & locations
Identify in the field by its reaction (fizzing) when exposed to a drop of diluted hydrochloric acid. Common in areas that were formerly ancient ocean floors.
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