sedimentary
Crushed Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale); Color: Gray to off-white; Luster: Dull to earthy; Crystal structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral
- Hardness
- 3 (Mohs scale)
- Color
- Gray to off-white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (Mohs scale); Color: Gray to off-white; Luster: Dull to earthy; Crystal structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral
Formation & geological history
Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It is also formed by the chemical precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Widely used as construction aggregate for road base and railroad ballast. It is also used as an ingredient in cement, an acid neutralizer in the chemical industry, and as a soil conditioner.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary mineral that forms karst topography, creating caves and sinkholes through natural dissolution.
Field identification & locations
Identify in the field by its softness (can be scratched by a copper coin) and its effervescence (bubbling) when it comes into contact with even weak acids like vinegar. Very common in regions with ancient seabed history.
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