sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness of 3 on Mohs scale, colors range from white to gray and tan, dull to earthy luster, fine-grained crystal structure, exhibits good cleavage.

Identified November 3, 2026More sedimentary →

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Physical properties

Hardness of 3 on Mohs scale, colors range from white to gray and tan, dull to earthy luster, fine-grained crystal structure, exhibits good cleavage.

Formed from the accumulation of skeletal fragments of marine organisms like coral, algal, and molluscan remains over millions of years.

Widely used in construction as building material, crushed stone for road bases, and as a primary raw material for manufacturing cement.

Limestone formations often host extensive cave systems due to the dissolution of calcium carbonate by slightly acidic groundwater.

Identified easily in the field through 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

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)