A metallurgical study of a few Coriosolite coins of the Trebry's hoard was carried out in correlation with the typological study and the neutron activation analysis of these coins. This analysis is destructive and so only a few coins which were obviously corroded have been studied. Metal structure and homogeneity were determined by optical microscopy. An electron probe micro analyzer (EPMA) identified the different constituents of the alloy. Tin, for example, which cannot be seen by neutron activation was detected in some phases using this method. This method is also very helpful in estimating the changes in corrosion through the coin by determining the distribution of oxygen and chlorine. Optical analysis also has provided information regarding the manufacture of ancient coinage; and some deviation in weight and copper abundances for a few coins, from their die-linked group, are explained.See also <i>AATA</i> <b>23-2837</b>. -- AATA