Handheld X-Ray Fluorescence Analysis (HH-XRF): a non-destructive tool for distinguishing sandstones in historic structures

摘要

Determining the provenance of building stone can be important when researching theudhistory of historic structures or identifying suitable substitute stone to use in buildingudrepairs. Commonly, however, there is no written record of stone source, and a visualudexamination alone is inconclusive. In many such situations stone provenance can only beudconstrained with confidence if the stone has a distinctive property or character that allows itudto be distinguished from, or matched with, other stones. A small proportion of stones haveudone or more genuinely distinctive visual characteristics that uniquely confirm theirudprovenance, but for most stones such distinctive properties, if they exist at all, are crypticudand usually revealed only by microscope examination or bulk chemical analysis. However,udcollecting and analysing representative hand samples for this purpose can be difficult, timeconsumingudand damaging to historic structures. Handheld X-Ray Fluorescence analysisudoffers the potential to provide bulk composition data without the need to collect physicaludsamples. HH-XRF instruments are lightweight, wireless and portable, and they provide audrapid, non-destructive means of analysing most materials in a wide range of settings. Thisudstudy has examined the benefits and limitations of the instrument when applied toudsandstone building stones from the UK. A programme of laboratory tests has been used to:uddevelop a robust methodology for gathering, managing, displaying and interpreting data;uddetermining the extent to which sample surface condition affects the analytical results; andudassessing the degree to which different sandstones can be distinguished on the basis of theirudbulk composition. The results are promising: the data can be used to compare, distinguishudand match visually indistinguishable sandstones (and potentially a wide range of otherudgeological and man-made materials) quickly and easily, and as such the method should findudwidespread application in disciplines such as building conservation and archaeology.