Production, Use or Deposition? An exploratory study into high phosphorus concentrations in archaeological ceramics

In chemical analyses studies of archaeological ceramics, high phosphorus concentrations are found regularly. Over the past decades multiple hypotheses regarding the origin of these high levels have been given, concerning the manufacture, use and burial environment of the ceramics. By focussing on how the phosphorus is distributed within the ceramic body and in which (mineral) form(s) it occurs, this thesis aims to gain a better understanding in the origin of these high phosphorus concentrations. This, in order to determine the potential of ceramic phosphorus analyses for archaeological research. A selection of ceramics with high levels of phosphorus was taken out of assemblages from four archaeological sites in the Netherlands: Maastricht Cannerberg (LBK), Voorschoten De Donk (middle and late Neolithic), Zandwerven (middle and late Neolithic) and Nijmegen Kops Plateau (Roman). Their chemical composition was analysed using XRF, after which an optical analysis using polarizing light...Show moreIn chemical analyses studies of archaeological ceramics, high phosphorus concentrations are found regularly. Over the past decades multiple hypotheses regarding the origin of these high levels have been given, concerning the manufacture, use and burial environment of the ceramics. By focussing on how the phosphorus is distributed within the ceramic body and in which (mineral) form(s) it occurs, this thesis aims to gain a better understanding in the origin of these high phosphorus concentrations. This, in order to determine the potential of ceramic phosphorus analyses for archaeological research. A selection of ceramics with high levels of phosphorus was taken out of assemblages from four archaeological sites in the Netherlands: Maastricht Cannerberg (LBK), Voorschoten De Donk (middle and late Neolithic), Zandwerven (middle and late Neolithic) and Nijmegen Kops Plateau (Roman). Their chemical composition was analysed using XRF, after which an optical analysis using polarizing light microscopy and fluorescence microscopy was carried out. Multiple deposits with different optical properties were found within the voids of the ceramic body. SEM-EDX was used to analyse the chemical composition of these deposits, as well as the chemical composition of the ceramic fabric itself. This study demonstrates phosphorus is present in large concentrations within the deposits in the voids, while the ceramic body has much lower concentrations. Since these voids have been formed during or after the firing process of the ceramics, there are no indications for accumulation of phosphorus during the manufacturing process of the ceramics. The SEM-EDX analysis of the deposits indicates the presence of different phosphate compounds, containing Ca, Fe and/or Al. No visible traces of chemical weathering were found within the ceramics, indicating the Al-phosphates, present in some of the deposits, did derive from the burial environment. Given that there are several different deposits that contain high phosphorus concentrations, there are potentially multiple mechanisms involved in this phenomenon.Show less

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Production, Use or Deposition? An exploratory study into high phosphorus concentrations in archaeological ceramics