Capital of the Abbasid Caliphate between 836 and 892 CE, the palace-city of Samarra offers a precise window into early Islamic art and architecture. Excavations conducted more than 100 years ago are seen as the beginnings of scientific Islamic archaeology, and have yielded an exceptional array of finds including a wealth of glass artefacts. The chemical composition of glass reflects the nature of the raw materials and their geological provenance and can therefore reveal past technologies and economic and cultural interactions. Through high-resolution analysis of a comprehensive glass assemblage from Samarra we have new evidence that points to the existence of an advanced Abbasid glass industry, as well as the import of specific glass objects for the thriving new capital city. Quantitative analytical data of 58 elements by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) show a striking correlation between object types and glass compositions. The compositional profiles of two related plant ash groups of architectural glass point to a local production, destined for the decoration of the famed glass walls of Abbasid palaces. The selective use of objects, materials and colours to create reflective and luminous glass walls are indicative of the great cultural and economic value of glass during the Abbasid period. Our findings thus confirm the veracity of written sources that stipulate the production of glass in the vicinity of Samarra, as well as the import of selected artefacts such as Byzantine mosaic tesserae.

The understanding of the glass trade in the first millennium CE relies on the characterisation of well-dated compositional groups and the identification of their primary production sites. 275 Byzantine glass weights from the British Museum and the Bibliothèque nationale de France dating to the sixth and seventh century were analysed by LA-ICP-MS. Multivariate statistical and graphical data analysis discriminated between six main primary glass types. Primary glass sources were differentiated based on multi-dimensional comparison of silica-derived elements (MgO, Al2O3, CaO, TiO2, Fe2O3, ZrO2) and components associated with the alkali source (Li2O, B2O3). Along with Egyptian and Levantine origins of the glassmaking sands, variations in the natron source possibly point to the exploitation of two different natron deposits. Differences in strontium to calcium ratios revealed variations in the carbonate fractions in the sand. At least two cobalt sources were employed as colouring agents, one of which shows strong correlations with nickel, indicating a specific post-Roman cobalt source. Typological evidence identified chronological developments in the use of the different glass groups. Throughout the sixth century, Byzantine glass weights were predominately produced from two glasses that are probably of an Egyptian origin (Foy-2 and Foy-2 high Fe). Towards the second half of the sixth century a new but related plant-ash glass type emerged (Magby). Levantine I was likewise found among the late sixth- to early seventh-century samples. The use of different dies for the same batch testifies to large-scale, centralised production of the weights, while the same die used for different primary production groups demonstrates the co-existence of alternative sources of supply. Given the comprehensive design of our study, these results can be extrapolated to the wider early Byzantine glass industry and its changes at large.

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We analysed a faience fragment from Bristol Museum and Art Gallery, to determine whether it belonged to the Town Mosaic, excavated at Knossos. Three Town Mosaic fragments from the Ashmolean Museum, Oxford were also examined. The objects were analysed using nondestructive variable-pressure scanning electron microscopy with energy-dispersive X-ray spectrometry. The Bristol object's composition and microstructures are similar to those of the Town Mosaic samples. Our results are also comparable to those from polished samples of Minoan faience (Tite et al. 2009), showing that VP SEM-EDX gives reliable results without invasive sampling. Silicaceous, copper-rich microspheres were identified for the first time in two of the Ashmolean objects.

In 1969-70, a single Tang dynasty blue-spotted Gongyi sherd was found at Siraf, Iran, the main trading port on the Persian Gulf in the early Islamic period. This is the only known example of Chinese blue-and-white ware, whether low-or high-fired, found in the Middle East from such an early date. The sherd provides direct archaeological evidence for the Indian Ocean trade between China and the Middle East in the ninth century AD. The body paste, clear glaze and blue glaze or pigment were analysed by thin-section petrography, scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX) and X-ray fluorescence (XRF). The technological analysis reveals the different steps of the chaîne opératoire: clay mixing, slip and glaze application, and decoration with the cobalt blue glaze before high-temperature firing. These steps are characteristic of Tang stoneware production at Gongyi in Henan province, China. The use of cobalt blue pigment as part of a simple spotted decoration scheme on the Gongyi sherd, and its find context within the Middle East, provides evidence for the complex interplay and influence occurring between Chinese and Middle East ceramic industries at this time.Closely comparable examples of contemporary low-fired earthenware ceramics with cobalt blue decoration on a white tin glaze manufactured within the Middle East also occur within the same assemblage from Siraf.