Metallic phases (sulphides, metallic compounds and metals), constitute critical components of metallurgical slags as they concentrate most of the potentially toxic metals occurring within smelting wastes. For this reason, a detailed characterization of the metal-rich phases is crucial for proper estimation of environmental threat resulting from slags deposition. Metallic phases observed in slags were transformed from the original ore minerals during metal smelting, and they constitute an interesting field for observations of sulphides and metals susceptibility to temperature and chemistry changes. In this study, we observed that compositions similar to sulphide minerals (e.g. bornite, chalcocite, pyrrhotite) are common, but they always appear in specific sets. We distinguished 3 general types of metallic phases: copper-iron-sulphur (among which the following subtypes appear: bornite-pyrrhotite, chalcocite, and chalcopyrite, all ofthese with various exsolutions), metallic copper and iron-phosphorous (Fe-P) type. Among all the distinguished types, Fe4Pproved to be most resistant to weathering whereas the Cu-Fe-S assemblage was altered strongly when not surrounded by glass or crystalline phases. Observations revealed that iron-rich metallic phases tended to appear in amorphous slags and copperrich phases occurring within crystalline samples.