Pliny the Elder testifies that roman workshops used volcanic glass (obsidian), but also produced and used a dark glass (obsidian-like glass) quite similar to the natural one. In the context of the study on medieval mosaics, the use of the obsidian and obsidian-like tesserae is a challenging research topic. In this paper, we present the results of a multidisciplinary study carried out on the Dedication wall mosaic, realized by a byzantine workshop in the 12th century in the Church of St. Mary of the Admiral in Palermo, and where numerous black-appearing tesserae, supposed to be composed of obsidian by naked-eyes observation, are present. Historical documents, multispectral imaging of the wall mosaic, and some analytical methods (SEM-EDS and XRPD) applied to a sample of black tesserae, concur in identifying here the presence of obsidian and different obsidian-like glass tesserae. This evidence, although related to the apparent tampering and restoration, could open a new scenario in the use of obsidian and obsidian-like glass tesserae during the Byzantine period in Sicily and in the reconstruction of multiple restoration phases carried out between 12 th and 20th century AD on the mosaics of St. Mary of the Admiral.

中文翻译：

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黑曜石和类似黑曜石的玻璃Tesserae：研究巴勒莫海军上将的圣玛丽教堂的奉献墙马赛克的多学科方法（12世纪）

老普林尼作证说，罗马作坊使用火山玻璃（黑曜石），但也生产和使用了与天然玻璃非常相似的深色玻璃（类似黑曜石的玻璃）。在中世纪马赛克研究的背景下，黑曜石和类似黑曜石的镶嵌物的使用是一个具有挑战性的研究课题。在本文中，我们介绍了对奉献墙马赛克进行的多学科研究的结果，该马赛克是由12世纪拜占庭式讲习班在巴勒莫的海军上将的圣玛丽教堂以及众多露面的黑色tesserae，存在由肉眼观察到的黑曜石构成的情况。历史文献，墙壁马赛克的多光谱成像以及一些分析方法（SEM-EDS和XRPD）适用于黑色镶嵌的样品，同意在此处确定黑曜石和其他类似黑曜石的玻璃镶嵌体的存在。该证据尽管与明显的篡改和修复有关，但可以为西西里岛拜占庭时期使用黑曜石和类似黑曜石的玻璃镶嵌以及在12至20世纪进行的多个修复阶段的重建开辟新的场景。在海军上将圣玛丽的马赛克上的广告。