sedimentary

Fossiliferous Limestone

Bioclastic Limestone (with Brachiopod and Bivalve molds)

AI-generated identification · may be incorrect

Hardness: 3-4 on Mohs scale; Color: Tan, buff, gray; Luster: Dull/Earthy; Structure: Clastic fossil fragments in a fine-grained carbonate matrix; Cleavage: None; Reacts vigorously with dilute HCl.

Hardness: 3-4 on Mohs scale
Color: Tan, buff, gray
Luster: Dull/Earthy

Identified June 22, 2026More sedimentary →

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Physical properties

Hardness: 3-4 on Mohs scale; Color: Tan, buff, gray; Luster: Dull/Earthy; Structure: Clastic fossil fragments in a fine-grained carbonate matrix; Cleavage: None; Reacts vigorously with dilute HCl.

Formation & geological history

Formed in shallow marine environments from the accumulation of skeletal remains like shells and coral. This specific specimen displays internal molds and casts of Paleozoic marine invertebrates, typically Carboniferous or Devonian in age.

Uses & applications

Used primarily in the construction industry as aggregate, dimension stone, or raw material for cement. High-quality fossil specimens are used for education and private collections.

Geological facts

The 'skull-like' appearance in the center is a coincidence of erosion on fossil molds, likely from brachiopods. These rocks provide a direct record of ancient sea floor life from millions of years ago.

Field identification & locations

Identify by looking for shell imprints and its characteristic fizzing when tested with acid. Commonly found in former marine basins and limestone quarries globally.