sedimentary

Crushed Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

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 July 3, 2026More sedimentary →

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Physical properties

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.