## 4 Conclusions  
In this work we present the chemical analysis of 48 glasses dated to the 6 th century CE excavated in Vasileos Irakleiou Street, 45. The samples are divided into moils and finished products, and based on the low K\({}_{2}\)O and MgO concentrations (<1.3 wt%) are both classified as natron glasses. The Na\({}_{2}\)O content is quite diverse, thus we can recognize two groups between our samples: the YK1 group with Na\({}_{2}\)O content < 15 wt%, and YK2 group with Na\({}_{2}\)O content > 15 wt%. The high TiO\({}_{2}\), Fe\({}_{2}\)O\({}_{3}\) and MnO contents of all glasses suggest an Egyptian origin and some of them are, also, comparable with HIMT 1 and HIMT 2 of [PERSON], 2009 [25] and others with Roman Mn or Roman Mn-Sb [10]. On the other hand, seven samples do not fit into the Egyptian type glasses and have probably experienced significant recycling. Furthermore, we suggest, based on the chemical analysis, that the finished products of the YK1 group and YK2 group have been produced by moils of the YK1 group and YK2 group, respectively. In addition, for all the samples, the great variance of Al\({}_{2}\)O\({}_{3}\) (1.6 wt% to 4.6 wt%) and CaO (4.4 wt% to 9.2 wt%) concentrations indicate multiple types of sand. Regarding the colorants, most of the samples have MnO content >1 wt%, implying its voluntary addition as a decolorizer, while in some samples (especially in YK2 group) MnO coexists with Sb\({}_{2}\)O\({}_{3}\). Finally, most of the samples present Sb\({}_{2}\)O\({}_{3}\), CuO, SnO\({}_{2}\), and P\({}_{2}\)O\({}_{5}\) in concentrations higher than those attributable to impurities in the raw materials, but too low to have any technological significance [3], hence, this is another factor that suggests recycling. The results of these analyses are very important for the archaeological research of the central Macedonian region, because they elucidate for the first time the chemical nature of the glass used for the production of major groups of objects produced in Thessaloniki's market in the late 6 th century. They also provide us with proofs of the trade of Egyptian raw materials, probably directly imported from Egypt, since it was raw glass imported from there that was in use in this centrally situated workshop. In addition, they prove that all statistically selected objects were indeed produced in the workshop of [PERSON] 45. Moreover, it shows that beakers, lamps, and glass gems were made--or discarded--at the same time as different batches of glass imported from the same region, probably loaded in ships at different times, or sold at the local market in different times. Further investigation has already begun with analysis of oxygen isotopes in the current samples, which will provide us with more evidence concerning the samples' origin. Additionally, more samples from the same region have been excavated in order to be analyzed.  
Figure 7: P\({}_{2}\)O\({}_{5}\) vs. K\({}_{2}\)O of Vasileos Irakleiou Street, 45 glasses.  
**Author Contributions:** Conceptualization, P.K. and E.D.; methodology, P.K. and E.D.; validation, E.D.; formal analysis: M.T. and A.E.P.; investigation, P.K., E.D., A.G. and A.A.; resources, E.D.; data curation, P.K., A.E.P. and M.T.; writing--original draft preparation, P.K. and E.D.; writing--review and editing, P.K., E.D., A.A. and A.G.; supervision, E.D. and A.G.; project administration, M.T. and A.E.P. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
**Data Availability Statement:** The data are available from the corresponding author upon request.  
The authors declare no conflict of interest.