sedimentary
Limestone
Sedimentary rock composed of Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: Gray, tan, white, or buff; Luster: Dull to earthy; Structure: Often contains visible grains or fossils; Specific Gravity: 2.5-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- Gray, tan, white, or buff
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (Mohs scale); Color: Gray, tan, white, or buff; Luster: Dull to earthy; Structure: Often contains visible grains or fossils; Specific Gravity: 2.5-2.7
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris; can also be formed by the chemical precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Primary source of lime for cement, used as a building stone, crushed stone for road base, and used as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Most caves are formed by the dissolution of limestone by acidic groundwater.
Field identification & locations
Can be identified in the field by its softness (scratched by a copper penny or steel) and its rapid effervescence (fizzing) when a drop of 10% hydrochloric acid is applied.
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