Natural preservation mechanisms at play in a Bronze Age wooden shovel found in the copper mines of Alderley Edge

A wooden shovel, dating from the Early Bronze Age, has survived in a remarkable state of preservation in the copper mines of Alderley Edge, Cheshire UK. Other historic timbers recovered from the mines, whilst still intact, have fared less well. An X-ray investigation into the distribution of minerals through the shovel using portable X-ray Fluorescence (PXRF) along with the use of synchrotron-based X-ray Absorption Spectroscopy (XAS) measurements of the copper and arsenic chemical speciations has provided clues to the methods by which metals from the mining environment have entered the wood of the shovel and ensured its survival. The distribution and nature of the minerals so determined suggest that the copper and arsenic, along with a significant lead content, entered the shovel during its original use in working mineral-rich deposits, rather than through the burial environment. The insights gained are expected to be applicable to other wooden artefacts recovered from ancient copper mines in other places. © 2011 Elsevier Ltd.