sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness 3 on the Mohs scale, typically white, gray, or buff in color, with a dull to earthy luster and fine-grained or crystalline structure.

Identified November 9, 2026More sedimentary →

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Physical properties

Hardness 3 on the Mohs scale, typically white, gray, or buff in color, with a dull to earthy luster and fine-grained or crystalline structure.

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

Extensively used in construction as building stone, aggregate in concrete, production of lime and cement, and in agriculture for soil conditioning.

Limestone frequently contains well-preserved fossils and dissolves slowly in acidic water, creating vast underground cave systems.

Easily identified by its light color and strong effervescence when dilute hydrochloric acid is applied; very common in sedimentary basins globally.

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)