sedimentary
Crushed Limestone
Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: Gray, beige, tan; Luster: Dull/earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral in calcite crystals but often obscured in aggregate
- Hardness
- 3-4 (Mohs scale)
- Color
- Gray, beige, tan
- Luster
- Dull/earthy
Identified More sedimentary →
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Physical properties
Hardness: 3-4 (Mohs scale); Color: Gray, beige, tan; Luster: Dull/earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral in calcite crystals but often obscured in aggregate
Formation & geological history
Formed principally through the accumulation of shell, coral, algal, and fecal debris in marine environments over millions of years (primarily Paleozoic to Mesozoic era).
Uses & applications
Used extensively as construction aggregate, road base, railroad ballast, and in the production of cement and lime. Also used as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is the primary source of carbon for carbon dioxide in the atmosphere when treated with acid or heat.
Field identification & locations
Identified by its reaction to dilute hydrochloric acid (it will fizz) and its ability to be scratched by a steel nail. Best found in quarry sites, road cuts, and regions with karst topography.
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