sedimentary
Limestone (or Calcite Pebble)
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Off-white, cream, pale beige; Luster: Earthy, dull; Structure: Microcrystalline/massive; Specific Gravity: ~2.7; Effervesces strongly with dilute acid.
- Hardness
- 3 on Mohs scale
- Color
- Off-white, cream, pale beige
- Luster
- Earthy, dull
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Physical properties
Hardness: 3 on Mohs scale; Color: Off-white, cream, pale beige; Luster: Earthy, dull; Structure: Microcrystalline/massive; Specific Gravity: ~2.7; Effervesces strongly with dilute acid.
Formation & geological history
Formed in shallow marine environments through the accumulation and compaction of organic debris (shells, coral) or chemical precipitation of calcium carbonate over geological time.
Uses & applications
Used widely in construction as crushed stone aggregate, cement manufacturing, soil conditioning in agriculture, and industrial chemical processes.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. Acid rain can gradually dissolve limestone structures due to its calcium carbonate content.
Field identification & locations
Identified in the field by its light color, soft hardness (scratched by a steel nail or copper penny), and reaction (fizzing) with weak acids like vinegar. Common worldwide in sedimentary basins and road gravels.
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