sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Cream, tan, or light grey; Luster: Dull to earthy; Crystal structure: Hexagonal (as calcite crystals); Cleavage: Perfect rhombohedral in calcite components; Specific gravity: 2.3 to 2.7.
- Hardness
- 3 on Mohs scale
- Color
- Cream, tan, or light grey
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Cream, tan, or light grey; Luster: Dull to earthy; Crystal structure: Hexagonal (as calcite crystals); Cleavage: Perfect rhombohedral in calcite components; Specific gravity: 2.3 to 2.7.
Formation & geological history
Formed primarily in marine environments through the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the chemical precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Extensively used in construction as aggregate, cement production, lime for soil treatment, and architectural stone.
Geological facts
Limestone covers about 10% of the total surface area of all sedimentary rocks on Earth. It often contains fossils of ancient marine life.
Field identification & locations
Identify in the field by testing with cold dilute hydrochloric acid; it will effervesce (fizz) vigorously. It is commonly found in extensive layered beds near ancient or current sea basins.
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