sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Off-white, gray, or tan; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (fractures irregularly).
- Hardness
- 3 on Mohs scale
- Color
- Off-white, gray, or tan
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Off-white, gray, or tan; Luster: Dull to earthy; Texture: Fine-grained to clastic; Cleavage: None (fractures irregularly).
Formation & geological history
Formed primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from ocean water or groundwater.
Uses & applications
Extensively used in construction as an aggregate, a key component in cement production, a building stone, and in agriculture as a soil conditioner (aglime).
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Many world-famous caves and karst landscapes are formed in thick limestone deposits through the acidity of groundwater.
Field identification & locations
Can be identified in the field by its effervescence (fizzing) when a drop of dilute hydrochloric acid is applied. Look for it in outcrop areas with visible bedding or fossil remains.
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