Production and provenance of architectural glass from the Umayyad period

PLoS One. 2020 Sep 28;15(9):e0239732. doi: 10.1371/journal.pone.0239732. eCollection 2020.

Abstract

A large assemblage (n = 307) of architectural glasses (tesserae and windows) from the early 8th-century Umayyad residential site at Khirbat al-Minya was analysed by laser ablation inductively coupled plasma mass spectrometry. Trace element patterns are essential to establish the provenance of the base glass, while the comparative evaluation of the colouring and opacifying additives allow us to advance a production model for the manufacture of glass mosaic tesserae during the early Islamic period. The primary glass types are Levantine I and Egypt 1a, as well as a few older, reused tesserae, and Mesopotamian plant ash glass used for amber-coloured window fragments. Chemical data revealed fundamental differences in the colouring and opacification technologies between the Egyptian and Levantine tesserae. Co-variations of lead and bismuth, and copper, tin and zinc in the Egypt 1a tesserae provide first evidence for the production of different mosaic colours in a single workshop, specialising in the manufacture of tesserae of different colours. No such trend is apparent in the Levantine samples. Red, cobalt blue and gold leaf tesserae were found to be exclusively made from a Levantine base glass, indicating that the generation of some colours may have been a specialised process. The same may apply to the amber-coloured window glass fragments of Mesopotamian origin that exhibit very unusual characteristics, combining elevated copper (2% CuO) with an excess in iron oxide (5% Fe2O3). These findings have significant implications for the production model of strongly coloured glass and the exploitation of resources during the early Islamic period.

Publication types

  • Historical Article
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Architecture / history*
  • Color
  • Coloring Agents / analysis
  • Copper / analysis
  • Egypt
  • Ferric Compounds / analysis
  • Glass / chemistry*
  • Glass / history*
  • History, 18th Century
  • Lead / analysis
  • Mass Spectrometry / methods
  • Middle East
  • Minerals / analysis
  • Tin / analysis
  • Trace Elements / analysis

Substances

  • Coloring Agents
  • Ferric Compounds
  • Minerals
  • Trace Elements
  • ferric oxide
  • Lead
  • bone ash
  • Tin
  • Copper
  • cupric oxide

Grant support

The project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 647315 to NS). URL: https://ec.europa.eu/programmes/horizon2020/en/h2020-section/european-research-council The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.