fossil

Tumbled fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃), with fossil shell fragments

AI-generated identification · may be incorrect

Brown, rounded and polished, with abundant pale fossil cross-sections and a dull-to-waxy luster. Calcite hardness is Mohs 3, with low specific gravity (~2.7); it effervesces strongly in dilute hydrochloric acid and may show indistinct bedding.

Identified September 4, 2026More fossil →

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Physical properties

Formation & geological history

Formed when marine shells and skeletal debris accumulated, were compacted, and cemented on an ancient seafloor; the exact geologic age cannot be determined from the image. Subsequent tumbling or polishing produced the smooth shape.

Uses & applications

Used as a decorative stone, cabochon, paperweight, and fossil specimen; limestone also serves as aggregate, cement feedstock, and building stone.

Geological facts

The visible circular and elongate markings are likely sections through shells, crinoid fragments, or other marine fossils rather than mineral crystals.

Field identification & locations

Common in marine sedimentary formations worldwide, especially fossiliferous limestone beds; inspect for acid reaction, visible biological textures, and absence of glassy conchoidal fracture.