## 3 Results and Discussion
In particular, most of the samples (finished glass and moils) are classified as Roman glasses, decolored by the addition of antimony and/or manganese, of the HIMT 1 and HIMT 2 type [25]. The HIMT 1 glasses are defined by high levels of iron (1.4 \(\pm\) 0.26 wt\(\%\) as Fe\({}_{2}\)O\({}_{3}\)), manganese (1.7 \(\pm\) 0.3 wt\(\%\) as MnO) and titanium (0.3 \(\pm\) 0.1 wt\(\%\) as TiO\({}_{2}\)), with PbO at 0.01 \(\pm\) 0.04 wt\(\%\), Sb\({}_{2}\)O\({}_{3}\) at 0.04 \(\pm\) 0.03 wt\(\%\) and CuO with a mean value of 91 ppm, and their yellow-green color is due to the amount of iron, suggestive of a relatively impure sand source [25]. In addition, the HIMT 2 glasses have lower content of the above oxides (i.e., 0.7 \(\pm\) 0.1 wt\(\%\) of Fe\({}_{2}\)O\({}_{3}\), 1.0 \(\pm\) 0.2 wt\(\%\) of MnO and 0.1 \(\pm\) 0.12 wt\(\%\) of TiO\({}_{2}\)) with higher PbO and Sb\({}_{2}\)O\({}_{3}\) contents of 0.02 \(\pm\) 0.04 wt\(\%\) and 0.09 \(\pm\) 0.05 wt\(\%\), and CuO with a mean value of 105 ppm, respectively [25]. These are, also, the key characteristics of Vasileos Irakleiou Street, 45 glass samples, which have high Fe\({}_{2}\)O\({}_{3}\) (1 to 2.7 wt\(\%\)), MnO (1 to 1.7 wt\(\%\)) and TiO\({}_{2}\) (0.1 to 0.38 wt\(\%\)) contents (Figure 5). Thus, these samples are not \"typical\" HIMT glasses, such as 'Group 1' in [PERSON] et al. [2003][9], showing a better fit with 'Group 2' [9], (dated to the late Antique period) and HIMT 1 and HIMT 2 in [PERSON], 2009 [25], which may be considered as \"weak\" HIMT glass due to lower contents of the key oxides of HIMT glass artefacts [25]. 'HIMT 1' glasses contain, on average, double the proportion of oxides of iron, manganese and titanium than that found in the \"weak\" HIMT samples. Additionally, we have seven samples (Y300G, Y300 AK, 317 TH, Y300 IB, 317 IB, 317 ST and Y300E) that can be recognized as outliers (Figure 4) as they do not fit strictly into any of the recognized Egyptian types due to both their high Al\({}_{2}\)O\({}_{3}\) (Figure 6) (above 3.5 wt\(\%\)) and their high K\({}_{2}\)O (above 0.9 wt\(\%\)) in combination with their P\({}_{2}\)O\({}_{5}\) (0.15 wt\(\%\) to 0.70 wt\(\%\)), concentrations implying that these glass samples have experienced significant recycling. Figure 5: Fe\({}_{2}\)O\({}_{3}\) versus TiO\({}_{2}\) (**a**), Fe\({}_{2}\)O\({}_{3}\) versus MnO (**b**) and Fe\({}_{2}\)O\({}_{3}\) versus Al\({}_{2}\)O\({}_{3}\) (**c**) of Vasileos Irakleiou Street, 45 glasses compared with bibliographic data [10; 25]. In Table 3 we have summarized the possible origin of each glass sample for this study. Furthermore, in Figure 6 we plotted the CaO and Al\({}_{2}\)O\({}_{3}\) concentration values of Vasileos Irakleiou Street, 45 glasses, in order to highlight the different lime/feldspar contents of the sand used for the production of the Vasileos Irakleiou Street, 45 glasses. The Vasileos Irakleiou Street, 45 glass finds can be compared with the known late/post Roman glasses such as the Roman Mn, the Roman Mn-Sb [10] and the \"HIMT 1 and 2\" group [25],  
Figure 6: CaO versus Al\({}_{2}\)O\({}_{3}\) of Vasileos Irakleiou Street, 45 glasses compared with bibliographic data [10,25]. \begin{table}
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and were, probably, produced in Egypt [8; 9]. These kinds of glasses are also found in the rest of the areas covered by the Roman Empire, as far as the Netherlands or the United Kingdom [8; 25]. The Vasileos Irakleiou Street, 45 glasses (Figure 6) appear to be mainly centered on the 'HIMT 1 and 2' area, confirming their age. Some glasses (mainly moils) are outside of the 'HIMT' area, confirming the use of recycled glass in glassmaking [12; 14]. Regarding the metal decolorants, most of our samples have significant amounts of both manganese and antimony. Glass production techniques refer to the addition of either MnO or Sb\({}_{2}\)O\({}_{3}\) as a decolorant agent, therefore the concomitance of these two oxides suggest a different production process [43].