sedimentary

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Carbonate composition reacts with dilute hydrochloric acid; Contains visible shell or skeletal fragments.

Hardness: 3 on Mohs scale
Color: Gray, tan, or white
Luster: Dull to earthy

Identified July 1, 2026More sedimentary →

Explore Fossiliferous Limestone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Carbonate composition reacts with dilute hydrochloric acid; Contains visible shell or skeletal fragments.

Formation & geological history

Formed in marine environments by the accumulation of shell, coral, algal, and fecal debris. These are organically derived sedimentary rocks typically from the Phanerozoic eon.

Uses & applications

Used in construction as building stone and aggregate for concrete, manufacturing lime, and as architectural decoration. Smaller fossils are popular for educational purposes.

Geological facts

Fossiliferous limestone is a biological record of ancient marine life. Entire mountain ranges, like parts of the Himalayas, are made of limestone that was once the floor of an ancient ocean.

Field identification & locations

Identify in the field by looking for visible fossil imprints or shell segments within the matrix; it can also be tested with acids for a characteristic fizzing reaction. Common in regions that were once prehistoric seafloors.