The glass walls of Samarra (Iraq): Ninth-century Abbasid glass production and imports
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.