Composition of Byzantine glasses from Umm el-Jimal, northeast Jordan: Insights into glass origins and recycling

Abstract

Twenty glass samples collected from four structures at Umm el-Jimal, northeast Jordan were analysed using the Electron Probe Micro-Analysis (EPMA). Except one ash-soda-lime-silica glass, all were natron-soda-lime-silica glasses of Levantine origin. Most of the glasses compositionally resemble glass from the Byzantine tank furnaces at Apollonia-Arsuf (Arsuf), but four with lower lime are closer to Umayyad period production at Bet Eli'ezer (Hadera). The paper presents diagnostic information indicating recycling in a Diagnostic Recycling Table (DRT) in which the analyses are ranked in a descending order of K2O, a key contaminant in the recycling process. This allows the comparison of a range of contaminant elements and it is observed that in general glass contaminated with fuel ash components K2O, P2O5 and CaO are also richer in transition metal oxides CuO, PbO, FeO and MnO, confirming that both sets of elements are important in identifying recycled glass. Chlorine is also identified as a component modified by recycling. The results ascertain that Umm el-Jimal was part of a major system of glass recycling in the Byzantine period, and emphasise the importance of recycled glass in its supply, in spite of its relative proximity to the location of raw glass production on the Syro-Palestinian coast.

Geochemistry of Byzantine and Early Islamic glass from Jerash, Jordan: Typology, recycling, and provenance

“…The manganese contents of raw glass from glass production sites in the Levant are below 250 ppm (Phelps, Freestone, Gorin‐Rosen, & Gratuze, ). This and other studies define a threshold for the natural background level of Mn in glass from the Levant around 250 ppm (Al‐Bashaireh, Al‐Mustafa, Freestone, & Al‐Housan, ; Brems & Degryse, ). Scatter plots of Mn versus other transition metals for the Jerash samples, show a strong correlation below 250 ppm, but samples with Mn above this value show a marked departure from the trend (e.g., Figure ).…”

“…Levantine glass has been divided into Levantine I type characterized by 68–71 wt% SiO 2 and 14–16 wt% Na 2 O and Levantine II type with relatively higher 73–76 wt% SiO 2 and lower 11–13 wt% Na 2 O contents (Freestone et al., ). More recently, it has been recognized that the original grouping of Levantine I incorporated the products of at least two different primary productions (Al‐Bashaireh et al., ; Phelps et al., ; Schibille et al., ) and that these can be more‐or‐less separated on the basis of composition: 6th–7th century CE glass from Apollonia (Freestone, Jackson‐Tal, & Tal, ; Tal, Jackson‐Tal, & Freestone, ) and 4th century CE glass from Jalame (Brill, ). Figure presents our data in terms of CaO/Al 2 O 3 and Na 2 O/SiO 2 ratios, which pull apart glass from the two production sites (Phelps et al., ) and also separate Apollonia glass from natron glass (previously Levantine II) from the Umayyad production site at Bet Eli'ezer, Hadera (Al‐Bashaireh et al., ).…”

“…More recently, it has been recognized that the original grouping of Levantine I incorporated the products of at least two different primary productions (Al‐Bashaireh et al., ; Phelps et al., ; Schibille et al., ) and that these can be more‐or‐less separated on the basis of composition: 6th–7th century CE glass from Apollonia (Freestone, Jackson‐Tal, & Tal, ; Tal, Jackson‐Tal, & Freestone, ) and 4th century CE glass from Jalame (Brill, ). Figure presents our data in terms of CaO/Al 2 O 3 and Na 2 O/SiO 2 ratios, which pull apart glass from the two production sites (Phelps et al., ) and also separate Apollonia glass from natron glass (previously Levantine II) from the Umayyad production site at Bet Eli'ezer, Hadera (Al‐Bashaireh et al., ). The reference data for Roman period Jalame glass are supplemented with data for Rom‐Mn glass from the 3rd century CE Iulia Felix wreck (Silvestri, ; Silvestri, Molin, & Salviulo, ) and for the Byzantine Apollonia‐type with the analysis of vessels from Palestine (Phelps et al., ).…”

“…This is possible, as typologically all of the forms could date to late Byzantine times or earlier. Furthermore, Bet Eli'ezer‐type glass has been identified at another site in Jordan, Umm el‐Jimal, located away from the coast but some 55 km to the North of Jerash (Al‐Bashaireh et al., ). However, an alternative explanation might be that, in the Umayyad period (661–750 CE), fresh glass from the coast was no longer reaching Gerasa and that the glass workers were entirely dependent upon recycled material.…”

The Corning Archaeological Reference Glasses: New Values for “Old” Compositions

“…These elements can be studied to understand technological processes involved in the making of glass. Sulphur concentrations can be an indicator of the chemical properties giving the glass its colour and the redox conditions of the furnace (Schreurs and Brill, 1984;Beerkens, 2003;Freestone and Stapleton, 2015), whereas chlorine concentrations serve as a marker of repeated melting or recycling (Al-Bashaireh et al, 2016), the addition of salt as a raw material (Gerth, Wedepohl and Heide, 1998;Wedepohl, 2003), and the melting temperature of the glass (Rehren, 2000). Both elements are also related to deterioration processes (Schreiner et al, 1999).…”