sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: white, tan, off-white with iron staining; Luster: dull to earthy; Crystal structure: Trigonal (microcrystalline); specific gravity: 2.5-2.7
- Hardness
- 3 on Mohs scale
- Color
- white, tan, off-white with iron staining
- Luster
- dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: white, tan, off-white with iron staining; Luster: dull to earthy; Crystal structure: Trigonal (microcrystalline); specific gravity: 2.5-2.7
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris, or by precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Used extensively in construction as road base, architectural stone, and a primary ingredient in cement and lime.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains fossils of ancient marine life like crinoids or mollusks.
Field identification & locations
Identify in the field by its softness (scratched by a copper penny or steel knife) and its reaction to dilute hydrochloric acid (it will fizz/effervesce). Found globally in sedimentary basins.
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