Chemical Compositions of Archaeological Glass

Glass pieces were highly appreciated goods in the Protohistory of the Iberian Peninsula. The specialized production of these glass pieces seems non-compatible with local workshops, and therefore, they are proof of commercial relationships with other cultures with the technical capability to produce such pieces. However, detailed studies of glass beads of archaeological relevance are scarce, as these samples usually appeared without a clear historical context. Nevertheless, the archaeological site of Pintia (Padilla de Duero, Valladolid, Spain) is a relevant exception to this situation. About 600 pieces have been recovered by 2018, with a significant percentage found in closed tombs. In this work, a set of 15 representati ve pieces from the Vaccaei culture (IV-I centuries BC) have been studied by Raman spectroscopy and ESEM/EDX. The combination of both techniques provided valuable information about the fabr ication of these samples, identifying diverse features that could be related to different workshops or origins. In particular, the characteristics of a sophisticated bifacial pendant were found to be compatible with their provenance from Carthage. Also, some of the pigments employed on these samples were identified by Raman spectroscopy, finding lead oxides, calcium antimoniate, hematite, and Naples yellow. The diverse trousseaus and viatic offerings found in the Vaccaei tombs show the relevance and complexity of the funerary cremation rituals in their culture. The study by Raman spectroscopy of well-preserved and thermally altered glass beads found in the same tomb allowed est imating the maximum temperature reached during the cremation in about 600 ºC, which confirmed previous estimations derived from the state of conservation of the bone remains.

With more published chemical analyses of glass beads in Southeast Asia and southern China in the last decade, it is becoming possible to discuss the regional and temporal patterns of prehistoric glass in these areas. This article focuses on the late 1 st millennium BC to the 1 st millennium AD, reviewing the chemical compositions of glass in Taiwan, Southeast Asia and southern China, in an attempt to understand the potential relationships between the three regions.

The chemical composition, as determined by electron probe X-ray microanalysis of a series of ca. 100 archaeological glass fragments, excavated at the Raversijde site (Belgium) is discussed. In the 15th-16th century, Raversijde was a flourishing fishermen town located on the shore of the North Sea, close to the city of Ostend. As a consequence of several battles that were fought in its vicinity, the site was abandoned in the 16th century and was not occupied since then. It is one of the rare archaeological sites in Europe that contains a significant amount of information on the daily life inside a small but affluent medieval community.

Статья представляет собой обзор основных результатов исследований, посвященных происхождению и распространению стекла в Восточном Средиземноморье и Европе в I тыс. н.э. Обобщены данные об элементном и изотопном составе стекла, происходящего из стекловаренных центров Египта и сиро-палестинского побережья. Данные о его распространении в Европе позволили исследователям реконструировать систему организации стеклоделательного  производства изучаемого периода и в ряде случаев определить источники поступления стекла-сырца (raw glass) в европейские вторичные мастерские.

In artefact compositional studies, the selection of variables to use in an analysis is unavoidable. Given this ubiquity , surprisingly little attention has been paid to ways in which variables might be selected. After arguing the case for the importance of variable selection, two systematic approaches to making a choice, which have had little or no application in archaeometry, are discussed and illustrated. One, based on the use of principal components, is appropriate if the structure is not known. The other, based on the use of classification trees,  is appropriate when there are know or assumed groups in the data.

In artefact compositional studies, the selection of variables to use in analysis is unavoidable. Given this ubiquity, surprisingly little attention has been paid to ways in which variables might be selected. After arguing the case for the importance of variable selection, two systematic approaches to making a choice, which have had little or no application in archaeometry, are discussed and illustrated. One, based on the use of principal components, is appropriate if structure in the data is not known. The other, based on the use of classi®cation trees, is applicable when there are known or assumed groups in the data.

This is the first broad survey using major, minor and trace element analyses of 8th–15th AD plant ash glass from the Middle East across a 2000 mile area stretching from Egypt to northern Iran. This was part of the ancient Silk Road that extended from the Middle East, through central Asia to China. Up to now, some compositional distinctions have been identified for such glasses mainly using major and minor element oxides and radiogenic isotopes. Our new trace element characterisation is for such glasses, mainly found in selected cosmopolitan hubs, including one where there is archaeological evidence for primary glass making. It provides not only far clearer provenance definitions for regional centres of production, in the Levant, northern Syria and in Iraq and Iran, but also for sub-regional zones of production. This fingerprinting is provided by trace elements associated with the primary glass making raw materials used: ashed halophytic plants and sands. Even more surprising is a correlation between some of the sub-regional production hubs and the types of glass vessels with diagnostic decoration apparently manufactured in or near the cosmopolitan hubs where the glass was found such as colourless cut and engraved vessels (in Iraq and Iran) and trail-decorated vessels (in the Levant). This therefore provides evidence for centres of specialisation. Our trace element characterisation provides a new way of defining the Silk Road by characterising the glass that was traded or exchanged along it. Taken together this data provides a new decentralised model for ancient glass production.