cobalt blue

Ingredients

cobalt ore, borax

Preparation Steps

Original Recipe Text

The elevated boron levels observed in the cobalt blue glass samples suggest the addition of borax during the pre-treatment of the cobalt ore (p. 8). This chemical signature aligns with instructions found in contemporary literary treatises regarding the processing of cobalt pigments for glazed tiles (p. 8). The cobalt colorant is also strongly correlated with iron, copper, and increased zinc levels (p. 8).

Evidence

"The 23 cobalt blue flasks form a very distinctive group (Fig 1D). ... The cobalt blue flasks exhibit also a distinct boron signature (Fig 4B)."

Remarks

These cobalt blue flasks were discovered in the 'harim' area south of the throne room of the Dār al-Khilāfa (p. 9). Their peculiar shape—elongated tubular bodies with necks that were crudely sawn off—suggests they served as branded packaging for valuable, light-sensitive contents (p. 9). Unlike the architectural glass, these flasks represent a centralized interregional trade, as their composition indicates they were imported from the eastern Mediterranean (Syria-Palestine or Egypt) rather than being produced locally in Mesopotamia (p. 8-9).