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Most of the large fragments are transparent with a blue-green colour, with a composition typical of recycled glass. X-ray fluorescence spectroscopy and scanning electron microscopy were used to investigate the raw materials, colorants and opacifiers employed to produce the glass assemblage. Fragments of glass vessels and glass beads were recovered from many of the cremation deposits, as they were commonly used during cremation rituals, and many of these had been affected by heat. Several different types of burial were identified during the excavation of the Roman military cemetery associated with the fort at Birdoswald, on Hadrian’s Wall (UK).
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![was ist natron was ist natron](https://i.pinimg.com/originals/c1/db/6b/c1db6b0b24da49653efdc262968a248a.jpg)
These include the possibility that, because of the massive scale of glass production, the demand for natron exceeded its supply the possible effect of climatic changes and the potentially disruptive role of political events in the Wadi Natrun–Delta region. The possible reasons for the apparent shortage of natron from 7th to 9th centuries AD and its subsequent replacement by plant ash as the flux used in glass production during the 9th century AD are then considered. Documentary evidence for possible natron sources in Egypt, including the Wadi Natrun, and around the eastern Mediterranean is summarised, and the results of recent fieldwork at the Wadi Natrun and at al-Barnuj in the Western Nile Delta are presented. In the present paper, the history of the use of natron as a flux is traced from its beginnings in the glaze of Badarian steatite beads, through its use in glass production starting in the 1st millennium BC, until its apparent shortage during the 7th to 9th centuries AD, and its subsequent replacement by plant ash during the 9th century AD. Natron deposits, the best known of which being those at Wadi Natrun in Egypt, have been used as the flux in the production of vitreous materials from the early 4th millennium BC onwards.