Where did the lustre tiles of the SIDI OQBA mosque (AD 836-63) in Kairouan come from?

Metallic lustre decoration of glazed ceramics is a very special kind of ornament, because its colours change with the observational conditions. In diffused light, they can be green, brown or ochre-yellow. In specular reflection, they show an associated coloured metallic shine (blue, golden-yellow or orange). The lustre tiles at the Sidi Oqba Mosque in Kairouan still have no defined origin (possibly Kairouan and/or Mesopotamia). Physicochemical analyses of eight Kairouan lustre tile samples and four Mesopotamian lustre pottery samples show that the Kairouan tiles probably came from Mesopotamia, from a major production centre, possibly Baghdad. Samarra or Basra.