sedimentary
Crushed Limestone
Sedimentary Carbonate Rock (CaCO3)
Hardness: 3 on Mohs scale; Color: typically grey, white, or tan; Luster: dull to earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral (not visible in aggregates); Specific Gravity: 2.5-2.7
- Hardness
- 3 on Mohs scale
- Color
- typically grey, white, or tan
- Luster
- dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: typically grey, white, or tan; Luster: dull to earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral (not visible in aggregates); Specific Gravity: 2.5-2.7
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in clear, warm, shallow marine waters. It can also form through chemical precipitation from ocean water or spring water. It is found in geological layers spanning from the Precambrian to the Holocene.
Uses & applications
Major use in construction as road base, concrete aggregate, and railroad ballast. Also used in the production of cement, for soil neutralization in agriculture, and as a source of industrial lime.
Geological facts
Limestone occupies about 10% of the total volume of all sedimentary rocks on Earth. Most of the world’s caves are formed in limestone because it is soluble in rainwater and weak acids.
Field identification & locations
Identify in the field by its grey color and fine-grained texture; it will effervesce (fizz) when exposed to a drop of dilute hydrochloric acid (or vinegar). Common in driveways and landscaping beds worldwide.
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