Geophysical survey is a staple ingredient of archaeological evaluation: variations in the earth’s magnetic field and soil resistivity are commonly used to map buried archaeological features. Geophysical; surveys allow archaeologists to plan excavations so that excavations are targeted on those areas that are most likely to produce the most informative results. Examining variations in soil chemistry (geochemical survey) has the potential to contribute in a similar way; however, conventional analytical techniques often involve a delay of months before results are available. Portable XRF allows the collection of geochemical data and reporting the next day (or even the same day). The technique has been applied successfully to better understand a Roman metalworking settlement. The variations in the lead concentration indicate those areas of the settlement where silver was being extracted from lead.
Using pXRF, a geochemical survey was carried out on a lead-working site in Somerset. The results compared and contrasted usefully with the geophysical results.