sedimentary

Fossiliferous Limestone

Calcium carbonate with biogenic inclusions (CaCO3)

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

Identified November 7, 2026More sedimentary →

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Physical properties

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

Formed from the accumulation and compaction of marine organism shells, coral, and skeletal fragments in shallow warm seas.

Used extensively in construction, cement production, agriculture, and as a decorative building stone.

Many famous historical monuments, including the Great Pyramids of Giza, are constructed largely from fossil-rich limestone.

Identify in the field by visible fossil fragments and a strong fizz test when exposed to dilute acid.

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)