sedimentary

Fossiliferous limestone pebble

Bioclastic limestone, commonly calcitic (CaCO₃)

AI-generated identification · may be incorrect

Brown, rounded, likely water-worn pebble containing abundant fossil shell or skeletal fragments in a fine calcite matrix. Calcite hardness is Mohs 3, vitreous to dull luster, non-cleavable as a rock, and reacts vigorously with dilute hydrochloric acid or vinegar.

Identified September 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from accumulated marine organisms, later cemented and lithified into limestone; the fossils may be Paleozoic to Cenozoic, but age cannot be determined from the image. Rounding indicates transport by a river, beach, or glacial environment.

Uses & applications

Used as decorative stone, aggregate, landscaping material, and educational fossil material; generally unsuitable for high-polish jewelry because calcite is soft and acid-sensitive.

Geological facts

The circular and irregular pale inclusions appear to be fossil fragments, possibly shells, crinoid debris, or small reef organisms. Exact identification requires a close view or thin section.

Field identification & locations

Common in marine sedimentary regions and gravel deposits. Check for acid fizz, inspect fossil shapes with magnification, and distinguish it from chert by its softness and acid reaction.