Mineralised organic remains from cesspits at the Roman town of Silchester: processes and preservation

Marshall, L.J.R., Almond, M.J., Cook, S.R., Pantos, M., Tobin, M.J. and Thomas, L.A. (2008) Mineralised organic remains from cesspits at the Roman town of Silchester: processes and preservation. Spectrochimica Acta Part A, 71 (3). pp. 854-861. ISSN 1386-1425 doi: 10.1016/j.saa.2008.02.037

Abstract/Summary

Mineralised organic remains (including apple pips and cereal grains) collected during the ongoing excavations of Insula IX at the Roman town of Silchester, Hampshire have been analysed by a combination of SEM-EDX, powder XRD and IR spectroscopy. The experiments included mapping experiments using spatially resolved versions of each technique. IR and powder XRD mapping have been carried out utilising the synchrotron source at The Daresbury Laboratory oil stations 11.1 and 9.6. It is concluded that these samples are preserved by rapid mineralisation in the carbonate-substituted calcium phosphate mineral, dahllite. The rapid mineralisation leads to excellent preservation of the samples and a small crystal size. The value of IR spectroscopy in studying materials like this where the crystal size is small is demonstrated. A comparison is made between the excellent preservation seen in this context and the much poorer preservation of mineralised remains seen in Context 5276 or Cesspit 5251. Comments on the possible mechanism of mineralisation of these samples are made. (C) 2008 Elsevier B.V.. All rights reserved.