sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: White to light grey; Luster: Dull to earthy; Structure: Clastic or crystalline; Cleavage: None; Specific Gravity: 2.71
- Hardness
- 3 on Mohs scale
- Color
- White to light grey
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: White to light grey; Luster: Dull to earthy; Structure: Clastic or crystalline; Cleavage: None; Specific Gravity: 2.71
Formation & geological history
Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form chemically through the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Major source for cement, building stone, lime production, glass making, and as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Many of the world's most famous caves are formed in limestone due to its solubility in slightly acidic water.
Field identification & locations
Identify in the field by its softness (scratches with a penny) and vigorous effervescence when exposed to dilute hydrochloric acid. Commonly found in ancient sea beds and karst landscapes.
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