sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, typically gray to tan in color, dull to earthy luster, and reacts strongly with hydrochloric acid.

Identified October 17, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, typically gray to tan in color, dull to earthy luster, and reacts strongly with hydrochloric acid.

Formed from the accumulation of skeletal fragments of marine organisms or chemical precipitation in shallow marine environments.

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

Limestone often contains well-preserved fossils and forms dramatic karst landscapes featuring caves and sinkholes.

Easily identified by its characteristic effervescence when exposed to acid; commonly found in quarries and sedimentary basins worldwide.

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)