Scrapheap Challenge Hallum: Archaeometallurgical investigation of a 3rd century bronze hoard

<p>In 2007 in the Frisian town of Hallum, a large copper depot was found in a ditch close to the town’s original dwelling mound. The 3rd century AD bronze hoard consists of over fourteen hundred thin-walled tableware fragments, including fragments of bronze cauldrons and pieces of Roman wine sieves. The depot is interpreted as tinker or coppersmith’s scrap metal. Using handheld XRF spectrometry the composition of the fragments was analysed to reconstruct the objects to determine the typology of the cauldrons.<br>In addition, the origin of the objects was determined by comparing the composition of the depot with the composition of eight Roman and local Iron Age reference data sets, six of which were collected during the course of this project. To gain insight in the composition and to identify clusters of objects with a similar composition, the compositional data of the Hallum hoard and the reference sets were plotted in histograms, scatter plots and ternary diagrams, and cluster analysis was performed. Furthermore, it was attempted to determine the level of recycling of the material based on the composition of the fragments.<br>The results show that the Hallum hoard consists of fragments from many (probably over hundred), incomplete objects. From most objects only a handful of fragments is present, making reconstruction impossible. However, the typology of the cauldrons could be determined based on the composition of the fragments. Most fragments probably originate from 3rd century Westland cauldrons and contemporary Sau type Östland buckets.<br>The origin of most fragments is probably Roman, as the distribution of the composition of the Hallum fragments matches the distribution of compositional data in the reference sets containing Roman objects. The hypothesis of a Roman origin for - at least part of - the Hallum material is further strengthened by the presence of Roman wine sieves fragments. However, it is unclear whether the objects crossed the border as complete, functional objects or as scrap metal. The composition and origin of the depot provide new insights into metalworking and trading in- and outside the Roman Empire.<br>The level of recycling was difficult to determine. The presence of a mix-series from brass to bronze suggests most brass fragments have been recycled. The level of recycling of the bronze objects is unclear, but this is expected to be low considering the standardistion of compositions.</p>