Modern coin debasement discovered by combined portable X‐ray fluorescence and atomic absorption spectroscopy in Peruvian cent coins (1950–1965)

Abstract

A series of one-and two-cent coins minted in Peru from 1950 to 1965 has been analyzed by portable X-ray fluorescence (pXRF), and the results have been calibrated by atomic absorption spectroscopy (AAS). These coins were expected to be composed of zinc and copper (95:5 wt/wt), but results show that the copper content changes from year to year and usually tends to be smaller than the legally acceptable limits (below 3 wt%). The nondestructive X-ray fluorescence analysis of the Cu/Zn ratio was calibrated with AAS. The pXRF results of 313 coins show a debasement over time with two minimums, one in 1954 (observed in both types of coins) and the second one in 1959 (present only in one-cent coins), in agreement with adverse economic events in this time frame. This is the first time that Peruvian coin debasement is studied with this particular nondestructive technique and correlated with a series of economic events in the country.

Analysis of South America coins of the XIX and XX centuries by XRF technique

“…al. [8] the one and two-cent coins of Sol de Oro were minted in Peru between 1950 and 1956 and removed from circulation after this period due to two global economic crises that strongly affected international zinc and copper prices. Besides that, according to the authors, the only period in which the Lima Mint (Casa Nacional de la Moneda, Peru) produced zinc coins was between 1931 and 1985.…”

“…The collection of 21 coins analyzed is a very representative sampling of two South American countries (Peru and Bolivia). The Peruvian coin "Sol de Oro" used from 1943 to 1965 and removed from circulation after two major events that affected the country economically [8]. Moreover, this collection includes twenty coins that tell the story of more than 1 century (1876 -1980) of mintage occurred in Bolivia and depict the evolution of the country's historical and economic context over this period, showing the different alloys used.…”