fossil

Tumbled fossiliferous limestone

Fossil-bearing micritic limestone, commonly containing crinoid or shell fragments

AI-generated identification · may be incorrect

Identified August 30, 2026More fossil →

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Physical properties

A brown, polished, fine-grained carbonate rock with pale fossil structures and veins; calcite composition, Mohs hardness 3, dull to waxy luster, massive microcrystalline texture, and weak-to-no cleavage in the specimen. It should effervesce strongly with dilute hydrochloric acid or vinegar, especially on a scratched surface.

Formation & geological history

Marine sediments compacted and cemented during the Paleozoic or Mesozoic, preserving skeletal fragments; the exact age and fossil identity cannot be determined from the image. Tumbling has rounded and polished the surface.

Uses & applications

Used as a decorative stone, lapidary material, educational specimen, and occasional cabochon or small ornament; not generally valuable for construction in this form.

Geological facts

The pale elongated markings may be crinoid-columnal or shell fragments, but image resolution prevents confident identification. Calcite-rich limestone is readily distinguished from harder silica-rich chert by its acid reaction and lower hardness.

Field identification & locations

Common in sedimentary basins worldwide, including the Midwest and Appalachian regions of North America, Europe, and parts of Asia. Test acid reaction, inspect fossils with a loupe, and avoid confusing it with jasper or chert.