In brief
The material and repetition of the supports are important for the reading of the ensemble.
Useful to know
Kairouan was founded in 670 and reached a significant heyday under the Aghlabids in the ninth century. Among its monuments is the Great Mosque with marble and porphyry columns, indicated in the UNESCO description. [1]
When considering an interior, it does not just follow the decoration of a separate column. Compare the rhythm of the supports and the way it separates or connects the space. Different material is not sufficient in itself for accurate dating. For the history of a particular element, an inscription, an archaeological study or a documented building sequence are needed.
Sources
For further detail and to check the information: