sedimentary

Fossiliferous limestone

Calcarenite/bioclastic limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3; pale cream to tan, earthy to dull luster, fine-grained matrix with visible shell fragments and irregular solution cavities. Calcite-rich material effervesces strongly with dilute hydrochloric acid and commonly shows no cleavage as a rock.

Identified August 9, 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

Formation & geological history

Forms from accumulated and cemented marine shell debris in shallow-water environments; the cavities may reflect dissolved shells or weathering. Age cannot be determined from the image and may range from Paleozoic to Cenozoic.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, and ornamental material; fossiliferous pieces are mainly collected for education and display. Value is generally modest unless fossils are exceptionally preserved or locality-significant.

Geological facts

The rounded fragments appear to be fossil shell material, while the darker opening is likely a dissolved fossil or weathering void. Limestone can develop karst landscapes and caves through carbonic-acid dissolution.

Field identification & locations

Common in marine sedimentary basins worldwide, including Florida, the Bahamas, the Mediterranean, and many coastal or former-seafloor regions. Confirm with acid fizz, relatively easy scratching by steel, and identifiable shell structure; avoid acid testing if preservation matters.