MAGNETIC-SUSCEPTIBILITY USED IN NONDESTRUCTIVE PROVENANCING OF ROMAN GRANITE COLUMNS

Magnetic susceptibility provides a rapid, cheap and non-destructive me thod of in situ characterization of archaeological artefacts containin g magnetic minerals, and can be used as an aid to geological provenanc ing. Three hundred and sixty-three Roman granite columns were measured by this method and results show clear groupings and similarities with potential granite sources in Italy, Turkey and Egypt. Magnetic suscep tibility measurements must be made on representative, unweathered surf aces of rocks and artefacts, and corrected for object size and surface relief according to manufacturers' recommendations. In addition, corr ections for column curvature have been derived for use with measuremen ts made on columns.