sedimentary

Limestone

Calcareous sedimentary rock (CaCO3)

Hardness is 3 on the Mohs scale. Colors range from white, gray, to tan, with a dull to earthy luster.

Identified November 14, 2026More sedimentary →

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Physical properties

Hardness is 3 on the Mohs scale. Colors range from white, gray, to tan, with a dull to earthy luster.

Formed from the accumulation of skeletal fragments of marine organisms like coral, algal, and mollusks in shallow warm marine waters.

Widely used in construction, as a building material, and as an aggregate for roads, as well as in the production of cement and agriculture.

Limestone often contains fossils and dissolves slowly in acidic water, creating dramatic cave systems and karst topography.

Can be easily identified in the field by its characteristic effervescence when dilute hydrochloric acid is applied.

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Sandstone or Siltstone

Arenite (if sandstone)

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Shale

Fissile Sedimentary Rock

Sandstone

Arenite

Shale

Clastic sedimentary rock