sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on the Mohs scale. Color: White, gray, tan, yellow, or brown. Luster: Earthy to dull. Crystal structure: Trigonal (as calcite). Cleavage: Perfect in three directions. Specific gravity: 2.71
- Hardness
- 3 on the Mohs scale
- Color
- White, gray, tan, yellow, or brown
- Luster
- Earthy to dull
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Physical properties
Hardness: 3 on the Mohs scale. Color: White, gray, tan, yellow, or brown. Luster: Earthy to dull. Crystal structure: Trigonal (as calcite). Cleavage: Perfect in three directions. Specific gravity: 2.71
Formation & geological history
Formed through the accumulation and compaction of organic remains such as shells, coral, and algal debris, or through the chemical precipitation of calcium carbonate from water in marine environments.
Uses & applications
Used extensively in construction (as building stone and aggregate), in the manufacturing of cement and lime, in agriculture to neutralize acidic soils, and as a chemical feedstock.
Geological facts
Limestone formations often house extensive cave systems due to the mineral's solubility in slightly acidic groundwater, creating impressive stalactites and stalagmites.
Field identification & locations
Can be easily identified by its reaction to dilute hydrochloric acid, which causes it to fizz or effervesce vigorously releasing carbon dioxide gas. Commonly found worldwide in sedimentary basins.
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