Fig 1.
Glass artefacts from Samarra representing the different compositional groups.
(A) Regularly shaped mosaic tesserae of natron type base glass (V&A A.58-1922); (B) glass inlays of plant ash group 1 (Sam 806.2, I. 9325.1, I. 9325.2, I. 9325.4; photos C. Krug, Museum für islamische Kunst / Staatliche Museen zu Berlin); (C) fragment of millefiori glass tile of plant ash group 2 (V&A C.743-1922); (D) cobalt blue flask neck (V&A C.750-1922); (E) rim fragment of painted glass bowl belonging to the miscellaneous samples (SamKat 273; photo M. Wypyski, Museum für islamische Kunst / Staatliche Museen zu Berlin). Images A, C and D from the Victoria and Albert Museum, London [http://collections.vam.ac.uk]; images B and E from the Museum für islamische Kunst / Staatliche Museen zu Berlin [www.smb-digital.de/eMuseumPlus].
Fig 2.
Different fluxing agents of the Samarra glasses.
K2O versus MgO concentrations identify differences between natron-type glasses, plant ash glasses from the Syro-Palestinian Islamic tradition and plant ash glasses of Mesopotamian provenance (sub-divisions are indicated by dashed lines).
Table 1.
Means and relative standard error of the mean (RSEM) of the five glass groups identified at Samarra.
Data [wt %] were reduced to the shown major, minor and trace element oxides and normalised to 100%.
Fig 3.
Analysis of the silica sources of the natron-type glasses from Samarra.
(A) CaO versus the ratio of TiO2 / Al2O3; (B) CeO2/ZrO2 versus Y2O3/ZrO2; (C) TiO2/Al2O3 versus Al2O3/SiO2.
Fig 4.
Variations in the plant ash component of the four plant ash groups.
(A) phosphorus compared to magnesium to calcium oxide ratios confirm different geographical origins; (B) boron and lithium concentrations (both normalised to the soda concentrations) identify different plant ash components and additives.
Fig 5.
Analysis of the silica sources of the plant ash groups from Samarra.
(A) differential zirconium and titanium correlations clearly distinguish the cobalt blue flasks from the other plant ash groups; (B) aluminium and iron concentrations indicate different degrees of silica related impurities; (C) selected trace elements, normalised to the upper continental crust compositions [36], highlighting the very low contaminants in plant ash group 1.
Fig 6.
The Samarra plant ash groups compared to contemporary glass assemblages.
Alumina versus magnesia to lime ratios of published data of glasses from Ramla [18], Tyre [44], Nishapur (Wypyski, in preparation) and Veh Ardasir [48, 49], indicating the proposed separation lines between early Islamic glasses from the eastern Mediterranean with low magnesia to lime ratios, the Samarra glass with high magnesia to lime ratios and low alumina levels, and Mesopotamian glasses with higher alumina concentrations typical of central Asian productions (lay-out of graph adapted from [18]).