sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness (Mohs scale): 3; Color: Grey, tan, off-white; Luster: Dull to earthy; Crystal structure: Trigonal (rhombohedral); Specific gravity: 2.3-2.7
- Color
- Grey, tan, off-white
- Luster
- Dull to earthy
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Physical properties
Hardness (Mohs scale): 3; Color: Grey, tan, off-white; Luster: Dull to earthy; Crystal structure: Trigonal (rhombohedral); Specific gravity: 2.3-2.7
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Used primarily in construction (crushed stone, cement manufacturing), agriculture (soil conditioner), and architecture.
Geological facts
Limestone occupies about 10% of the total volume of all sedimentary rocks. It is the primary material found in famous landmarks like the Great Pyramids of Giza.
Field identification & locations
Identify in the field by its softness (can be scratched by a steel point) and its effervescence (bubbling) when in contact with dilute hydrochloric acid. Commonly found in quarries and cliff faces.
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