sedimentary

Limestone

Calcium Carbonate (CaCO3)

Mohs hardness of 3, colors range from white to gray and tan, dull to earthy luster, fine-grained to microcrystalline structure.

Identified October 18, 2026More sedimentary →

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Physical properties

Mohs hardness of 3, colors range from white to gray and tan, dull to earthy luster, fine-grained to microcrystalline structure.

Formed by the accumulation of organic remains like shells and coral, or chemical precipitation in marine environments over millions of years.

Widely used in construction, cement production, agriculture to neutralize soil acidity, and as a dimension stone.

Limestone frequently contains well-preserved fossils and forms dramatic karst landscapes with caves and sinkholes.

Identified by its characteristic reaction to dilute hydrochloric acid, which causes it to fizz and release carbon dioxide.

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

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)