sedimentary

Fossiliferous limestone

Bioclastic limestone (calcite-rich carbonate rock)

AI-generated identification · may be incorrect

Typically Mohs 3–4; gray-brown matrix with abundant pale fossil fragments, calcite veins or cement, and dull to slightly waxy luster. It is commonly massive, lacks foliation, and may fizz vigorously with dilute hydrochloric acid.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when shells and skeletal debris accumulate on a shallow marine seafloor, become compacted, and are cemented by calcite. The specimen’s exact geologic age cannot be determined from the image; such limestones range from Paleozoic to recent deposits.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, and occasionally as a decorative or educational specimen. Its collector value is generally modest unless the fossils are exceptionally identifiable or from a notable locality.

Geological facts

The white clasts appear to be fossil fragments—possibly shell, crinoid, or other marine bioclasts—rather than crystals. Acid testing and close examination of cross-sections can distinguish it from conglomerate.

Field identification & locations

Common in former shallow-sea regions worldwide, including the United States, Europe, and the Caribbean. Look for fossil shapes, carbonate fizz, relatively low hardness, and powdery white streak; avoid acid testing on polished surfaces.