sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: white, cream, or gray; Luster: dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific gravity: 2.7
- Hardness
- 3 on Mohs scale
- Color
- white, cream, or gray
- Luster
- dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: white, cream, or gray; Luster: dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral; Specific gravity: 2.7
Formation & geological history
Formed primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from calcium-rich waters.
Uses & applications
Extensively used as a building material, aggregate for concrete, manufacture of lime and cement, and in the production of steel and glass.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary material found in many of the world's most famous caves and karst landscapes.
Field identification & locations
Can be identified in the field by its reaction to dilute hydrochloric acid (effervescence) and its relatively soft surface that can be scratched with a penny. Commonly found in former seabed locations.
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