sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs); Color: White, grey, or tan; Luster: Dull/Earthy; Crystal Structure: Trigonal (as calcite); Specific Gravity: 2.5-2.7
- Hardness
- 3-4 (Mohs)
- Color
- White, grey, or tan
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3-4 (Mohs); Color: White, grey, or tan; Luster: Dull/Earthy; Crystal Structure: Trigonal (as calcite); Specific Gravity: 2.5-2.7
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters over millions of years.
Uses & applications
Used extensively in construction (road base, concrete), agriculture (soil conditioner), and industrial manufacturing of glass and steel.
Geological facts
Limestone is the source of approximately 10% of the world's sedimentary rocks. It is also the primary material found in famous locations like the Great Pyramids and the White House.
Field identification & locations
Identify in the field by its reaction to dilute hydrochloric acid (effervescence) and its ability to be scratched by a steel blade. Found in abundant quantities globally.
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