fossil

Fossiliferous limestone

Bioclastic carbonate rock, chiefly calcite (CaCO₃), containing fossil fragments—possibly coral or bryozoan

AI-generated identification · may be incorrect

Typically gray-beige, fine to medium grained, with lighter fossil patterns and dull to weakly vitreous luster; calcite is Mohs 3 and reacts vigorously with dilute hydrochloric acid. Usually massive, without prominent cleavage; specific gravity is about 2.6–2.8.

Identified August 29, 2026More fossil →

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Physical properties

Formation & geological history

Forms when marine skeletal debris accumulates, is compacted, and cemented on a shallow seafloor; the visible fossils may be Paleozoic to Cenozoic, but age cannot be determined from the image alone.

Uses & applications

Used as a decorative or educational specimen and, when abundant and sound, as aggregate, building stone, or cement raw material; generally unsuitable for jewelry except as a polished cabochon.

Geological facts

The branching and segmented markings appear biological rather than crystalline, consistent with fossilized colonial organisms or shell material preserved in limestone.

Field identification & locations

Look for acid fizz, relatively low hardness, and fossil shapes that remain continuous across the cut or weathered surface; common in marine sedimentary formations worldwide. Value is usually about $5–$30 for a hand specimen, or $30–$100+ if the fossil detail and provenance are especially good.