sedimentary

Tumbled fossiliferous limestone

Micritic limestone, likely bioclastic/fossiliferous carbonate rock (predominantly CaCO₃)

AI-generated identification · may be incorrect

Brown, smoothly polished, dull-to-waxy luster with abundant small fossil or pore-like cavities; hardness about 3–4 Mohs, massive and non-cleavable. Likely reacts weakly to strongly with dilute hydrochloric acid, especially on a fresh surface.

Identified September 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from lithified carbonate mud and accumulated marine skeletal material, commonly during Paleozoic–Mesozoic marine sedimentation; the exact age cannot be determined from the photograph. Tumbled and polished after collection.

Uses & applications

Used as a decorative stone, paperweight, teaching specimen, and occasional lapidary material; generally unsuitable for durable jewelry because limestone is relatively soft and acid-sensitive.

Geological facts

The rounded holes may be fossil fragments, dissolved shell cavities, or secondary vugs rather than true vesicles. Brown coloration commonly comes from iron-bearing impurities or organic matter.

Field identification & locations

Look for carbonate reaction, visible shell textures, and a calcite-rich composition; distinguish it from volcanic rock by its softness and lack of igneous crystals. Common sources include marine limestone regions worldwide.