Application of X-ray Fluorescence to Numismatics. Medal study of Cuban schools (1850-1960)

Abstract

This work presents the determination of intrinsic values (metal alloy composition) of medals, using a laboratory
developed portable X-Ray Fluorescence (XRF) spectrometer based in miniaturized low power X-ray tube (max. 50 kV 1
mA, Pd anode) and Si-PIN detector. The analyses were carried out without sampling or contact with surface of medals.
The application of this non destructive analytical method in Numismatic is demonstrated and exemplified with the study
of a collection of Cuban primary schools medals (1850-1960). The medals are characterized through the concentrations of
metals and pigments. Anachronisms and metal alloy were identified in medals of year’s 50s (XX). Questions about Cuban
or North American provenance or attribution to specific Cuban jeweller’s workshop of the non marked medals of the
collection were answered through the analysis of bivariate plots of XRF characteristic line area of marker metals: Ni/Cu
vs. Zn/Cu y Au/Cu vs. Zn/Cu. Significant differences between attributed medals of the Havana’s jewelleries: Fuentes &
Alvarez and Bustamante y Hnos. and the North American jewelleries: Art Co. and Green Duck Co., which allows to
attribute the non marked medals granted by Cuban schools . The metal concentrations of 22 most important medals of
this collection were calculated using the external standard method and certified standard reference materials.