A Metallurgical Provenance Study of the Marcus Herennius Military Diploma

The bronze used to make the military diploma for the Roman soldier Marcus Herennius in AD 109 is heterogeneous in texture and com­position. In contrast to modern bronze, lead (Pb) inclusions are common, and the bronze shows a considerable range in copper (Cu) (73 to 92.7 weight percent) and tin (Sn) (6.1 to 26.5 weight percent). Lead isotopic com­positions are identical to those of copper coins produced during the Impe­rial Era of Augustus and Tiberius and may indicate mixtures of ores from southeastern Spain and Sardinia. The combination of these analytical results provides permissive evidence that the plates are authentic artifacts manufactured at the turn of the second century AD.

Published in BYU Studies Quarterly 45:2
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