sedimentary

Fossiliferous Limestone

Fossiliferous Calcarenite (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Cream, tan, or grey; Luster: Dull to earthy; Structure: Clastic or biogenic with visible fossil clasts; Reacts strongly with dilute HCl acid.

Hardness: 3 on Mohs scale
Color: Cream, tan, or grey
Luster: Dull to earthy

Identified June 28, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Cream, tan, or grey; Luster: Dull to earthy; Structure: Clastic or biogenic with visible fossil clasts; Reacts strongly with dilute HCl acid.

Formation & geological history

Formed in marine environments through the accumulation of calcium carbonate shells, skeletal fragments, and coral debris that are later cemented together during lithification. Most dates from the Phanerozoic eon.

Uses & applications

Used in construction as a building stone or aggregate, as a source for lime (calcium oxide) in agricultural and industrial processes, and as a popular specimen for educational fossil collecting.

Geological facts

This specific piece is coquina-like, containing gastropod or bivalve shells. Large portions of the Great Pyramids of Giza are constructed from fossiliferous nummulitic limestone.

Field identification & locations

Look for visible sea shells or fragments embedded in a fine-grained, light-colored matrix. Common in coastal regions or areas that were ancient sea beds. Soft enough to be scratched by a steel nail.