Sedimentary Concretion

This specimen is a well-rounded sedimentary concretion, formed by the localized precipitation of mineral cement within unconsolidated sediment during early diagenesis. The smooth, ellipsoidal form and uniform texture are characteristic of concretions that develop around a nucleus—such as organic material, shell fragments, or subtle chemical irregularities—before the surrounding sediment fully lithifies.

The fine-grained, grey to greenish-grey matrix suggests a mudstone or siltstone host, with localized iron-oxide staining visible on fractured surfaces. Concretions such as this are common in marine and lacustrine sedimentary environments and are valued in collections for illustrating post-depositional geological processes rather than representing a single mineral species.

This specimen is catalogued conservatively due to the absence of locality data and has been retained as an educational example of sedimentary diagenesis.

85 x 45 x 45mm

268g