Monnaies arvernes (Vercingétorix, Cas) en orichalque

The two coins bearing Vercingetorix's name and the four coins belonging to the "CAS" série, until now considered as bronzes and struck at the type of gold staters are actually brass coins. If the hypothesis that these particular coins constitute the witness of "obsidional" coinage seems very likely, as far as we know, analytical data pose the problem of their manufacture in the context of Alesia's battle in 52 B.C.