sedimentary

Fossiliferous Limestone

Biogenic Sedimentary Rock (CaCO3)

Hardness of 3 on the Mohs scale, grayish-brown color, dull to earthy luster, composed of compacted fossil fragments with calcite cement.

Identified October 24, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, grayish-brown color, dull to earthy luster, composed of compacted fossil fragments with calcite cement.

Formed in shallow marine environments through the accumulation and compaction of shelly organic debris over millions of years.

Used widely in construction as crushed stone, dimension stone, and for manufacturing Portland cement.

Fossiliferous limestone often preserves ancient marine ecosystems, containing visible crinoids, brachiopods, and bryozoans.

Easily identified by its reaction to dilute hydrochloric acid, which causes it to effervesce due to calcium carbonate content.

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)