sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness: 3 (Mohs scale), Color: White, grey, or tan, Luster: Dull to earthy, Crystal Structure: Trigonal (as calcite), Cleavage: Perfect rhombohedral, Specific Gravity: 2.7
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Physical properties
Hardness: 3 (Mohs scale), Color: White, grey, or tan, Luster: Dull to earthy, Crystal Structure: Trigonal (as calcite), Cleavage: Perfect rhombohedral, Specific Gravity: 2.7
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from lake or ocean water.
Uses & applications
Primary source of lime for cement, used as a building stone (dimension stone), aggregate for road bases, and as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary rock found in karst landscapes, which are characterized by caves and sinkholes.
Field identification & locations
Can be identified in the field by its softness (can be scratched by a copper coin) and its strong effervescent reaction to dilute hydrochloric acid. Commonly found in thick beds around the world.
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