Analysis of copper and brass coins of the early roman empire

Science. 1966 Jan 14;151(3707):196-7. doi: 10.1126/science.151.3707.196.

Abstract

X-ray fluorescence analysis of 14 copper and brass coins of the early Roman Empire shows differences in composition between coins minted in Rome and in France. Concentrations of tin, lead, and antimony are nearly always less than in coins minted before 29 B.C. or after 54 A.D. Older coins were not melted to make copper coins of the early empire.