Glass – one of the most prestigious materials of the early Islamic empire – was traded not only as vessels and bangles but as raw glass blocks. One of its raw materials, plant-ash, was also traded. This means that tracking the production of this precious commodity is especially challenging. The authors show that while chemical composition can relate to vessel type, it is a combination of chemical compositions with strontium and neodymium isotope ratios that is most likely to lead to (a geological) provenance for its manufacture. The materials used by the glassmakers were local sand and plant ashes. Reported here is the first application of the method to the glass made at the primary glass making centre of al-Raqqa, Syria in an environmental context.