sedimentary

Limestone

Sedimentary rock composed mainly of calcium carbonate (CaCO3)

Hardness of 3 on the Mohs scale, typically white to gray or yellowish in color, dull to earthy luster, and reacts with dilute hydrochloric acid.

Identified November 5, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, typically white to gray or yellowish in color, dull to earthy luster, and reacts with dilute hydrochloric acid.

Formed from the accumulation of skeletal fragments, coral, or chemical precipitation in marine environments over millions of years.

Widely used in construction as building stone, aggregate for roads, and in the production of cement and agricultural lime.

Limestone often contains well-preserved fossils and can form spectacular karst topography features like caves and sinkholes.

Identified by its pale color, soft texture, and characteristic fizz when tested with acid; found worldwide in sedimentary basins.

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)