Microstructure and chemical composition of Thracian medallions with enamel in millefiori technique found in Bulgaria

The objects of investigation are three medallions. Both of them are made with copper alloy plating from Thracian chariot found in the Plovdiv region, Bulgaria. The dating of medallions is made in accordance with the construction of the chariot: 1st–4th centuries AD. The medallions are richly decorated with enamel in millefiori technique showing a variety of colored glasses. The third medallion is from Alfatar, Bulgaria. Adornments of this type are unique for present day Bulgaria. The aim of this work is to begin a detailed study of these rare archaeological objects to determine their technological features and to compare them with some similar artefacts from other lands. A combination of relatively non-destructive, structurally sensitive, methods as: transmission electron microscopy (TEM), selected area electron diffraction SAED and electron probe microanalysis (EPMA) is applied on small samples of the medallions. From obtained data we conclude that the composition corresponds to the composition of similar enamels dating from the same period. The observed microstructure of some glasses in the decoration of the medallions is due to the weathering processes and the technological history of the medallions.