sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Tan, gray, or white; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.5-2.7
- Hardness
- 3 on Mohs scale
- Color
- Tan, gray, or white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Tan, gray, or white; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.5-2.7
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. Can also form through chemical precipitation from lake or ocean water.
Uses & applications
Extensively used in construction (concrete), as a base for roads, as a pigment or filler in products like toothpaste or paints, and in the production of lime.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains fossils that provide a record of ancient marine life.
Field identification & locations
Identify in the field by its reaction (fizzing) with diluted hydrochloric acid. It is commonly found in karst landscapes and coastal areas.
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