fossil

Polished fossiliferous limestone

Fossiliferous micrite/bioclastic limestone, likely crinoidal or shell-rich limestone

AI-generated identification · may be incorrect

Dark gray to black, polished, fine-grained carbonate containing numerous circular fossil cross-sections; calcite composition, Mohs hardness 3, dull to glossy polish, and typically massive structure with no cleavage visible. It may fizz weakly with dilute hydrochloric acid.

Identified September 9, 2026More fossil →

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Physical properties

Formation & geological history

Formed when marine skeletal debris accumulated, compacted, and cemented as limestone, commonly during the Paleozoic or Mesozoic eras. The circular patterns are likely fossil fragments such as crinoid stems, shells, or coral.

Uses & applications

Used as a decorative polished stone, cabochon, paperweight, or educational fossil specimen; not generally used structurally in this small polished form.

Geological facts

The repeated ring-like features preserve marine organisms in cross-section and are characteristic of fossiliferous carbonate rocks. Exact fossil identification requires magnification and locality information.

Field identification & locations

Look for visible fossil outlines, carbonate softness, and acid effervescence; common sources include fossil-bearing limestones in the United States, United Kingdom, Europe, and North Africa. Avoid prolonged acid testing because it damages the polish.