PIXE, XRF and GRT for the global investigation of ancient gold artefacts

The study of ancient gold jewellery artefacts often requires surface and bu lk characterisation using Iron-destructive methods. Curators of musea or ow ners of private collections do not allow any sampling (even at microscopic level) for the investigation of the bulk of massive gold objects, which oft en contain less noble metals, Neutron Activation Analysis of the whole samp le is generally prohibited even if no danger may be feared from delayed rad ioactivity. Weight and density measurements are easy and convenient to asse rt the presence of a cavity or a core of lower density. A combination of PI XE (at various incident proton energies in a non-vacuum geometry) for the e lemental distribution in the first 10 mu m below the surface, XRF (induced by gamma-rays of 59 keV and of higher energy from a source of Am-241) to in vestigate the material up to several hundreds of microns, and GRT (Gamma Ra y Transmission) of 662 keV photons (Cs-137) may give a more complete answer on the surface and bulk compositions of the artefacts. Examples are given for Hellenistic and Mesoamerican jewellery items. (C) 1999 Published by Els evier Science B.V. All rights reserved.