sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness: 3 on Mohs scale; Color: Light beige, tan, gray; Luster: Dull, earthy; Texture: Fine-grained to microcrystalline; Cleavage: None (conchoidal to irregular fracture); Specific Gravity: 2.5–2.7.
- Hardness
- 3 on Mohs scale
- Color
- Light beige, tan, gray
- Luster
- Dull, earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Light beige, tan, gray; Luster: Dull, earthy; Texture: Fine-grained to microcrystalline; Cleavage: None (conchoidal to irregular fracture); Specific Gravity: 2.5–2.7.
Formation & geological history
Formed primarily in shallow, warm marine environments through the accumulation and compaction of organic debris like shells and coral, as well as chemical precipitation of calcium carbonate over millions of years.
Uses & applications
Widely used as building material, crushed stone for road base, lime production in agriculture, cement manufacturing, and soil stabilization.
Geological facts
Limestone reacts strongly with dilute acid (effervesces), releasing carbon dioxide gas. It forms dramatic karst landscapes featuring caves, sinkholes, and underground rivers over geological time.
Field identification & locations
Can be easily identified in the field using a drop of weak acid (such as vinegar or dilute HCl) which causes it to fizz. Found globally in sedimentary basins, ancient seabed deposits, and quarry sites.
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