Down to the Crust: Chemical and Mineralogical Analysis of Ceramic Surface Encrustations on Bronze Age Ceramics from Békés 103, Eastern Hungary

Békés 103, a primarily Middle Bronze Age (c. 1600–1280 calBC) cemetery and settlement on the Great Hungarian Plain, has been investigated by the BAKOTA project since 2011. Ceramics from the site are covered in dense white concretions, and it has been noted during compositional analyses that these vessels exhibit elevated concentrations of several potentially mobile elements in comparison to vessels from regional tell sites. Here, we use a multimethod (optical mineralogy, FT-IR, XRD, XPS, PXRF, SEM-EDS, and LA-ICP-MS) mineralogical and chemical approach to characterize the composition of surface encrustations on ceramics samples from Békés 103. We also chemically map interior paste composition using LA-ICP-MS to identify potential leaching of mobile elements into or out of vessel bodies. We demonstrate that the surface encrustations are primarily composed of calcite but also contain a variety of other mineral and organic constituents indicative of deposition of soil carbonates, phosphates, nitrates, and other inorganic and organic components. We further document the leaching of several mobile elements into ceramic pastes as well as formation of secondary calcite along void, pore, and temper boundaries. The presence of cremated bone and possibly bone ash in close vicinity to many of the studied vessels may also have contributed to the observed patterns of diagenesis. It is likely that similar post-burial processes might affect ceramics from other sites located in low-lying, seasonally inundated contexts.