sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale. Color: Tan, beige, light brown, grey. Luster: Dull to earthy. Texture: Very fine-grained to microcrystalline. Reaction: Effervesces (fizzes) strongly in dilute hydrochloric acid.
- Hardness
- 3 on Mohs scale
- Color
- Tan, beige, light brown, grey
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale. Color: Tan, beige, light brown, grey. Luster: Dull to earthy. Texture: Very fine-grained to microcrystalline. Reaction: Effervesces (fizzes) strongly in dilute hydrochloric acid.
Formation & geological history
Formed by the accumulation and compaction of organic debris like shells, coral, and microfossils, or through chemical precipitation of calcium carbonate from marine or freshwater environments over millions of years.
Uses & applications
Widely used as a aggregate in construction, manufacturing of cement, lime production, soil conditioner in agriculture, and building stone.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary rock type in which karst topography, such as caves, sinkholes, and underground drainage systems, develops.
Field identification & locations
Can be identified in the field by its softness (scratchable with a steel nail or copper penny) and immediate reaction (fizzing) when exposed to weak acid like vinegar or HCl. Extremely common worldwide.
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