sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on the Mohs scale. Color: typically gray, white, yellow, or brown. Luster: dull to earthy. Crystal structure: hexagonal (calcite). Cleavage: perfect rhombohedral. Specific gravity: 2.7.
- Hardness
- 3 on the Mohs scale
- Color
- typically gray, white, yellow, or brown
- Luster
- dull to earthy
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Physical properties
Hardness: 3 on the Mohs scale. Color: typically gray, white, yellow, or brown. Luster: dull to earthy. Crystal structure: hexagonal (calcite). Cleavage: perfect rhombohedral. Specific gravity: 2.7.
Formation & geological history
Formed over millions of years through the accumulation and compaction of organic remains such as shells, coral, and algal debris in marine environments.
Uses & applications
Widely used in construction (cement and concrete production), agriculture (soil conditioning), and as a building stone.
Geological facts
Limestone often contains marine fossils and reacts with dilute hydrochloric acid by effervescing (bubbling), releasing carbon dioxide.
Field identification & locations
Found worldwide in sedimentary basins, cliffs, and caves. Readily identified by its reaction to acid and its relatively soft nature.
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