Chemical characterization of glass beads from the necropolis of Dren-Delyan (6 th –4 th century BC), Southwest Bulgaria

Author: Nikoleta, Published:

Tzankova, N., Mihaylov, P. 2019. Chemical characterization of glass beads from the necropolis of Dren-Delyan (6th–4th century BC), Southwest Bulgaria. Geologica Balcanica 48 (2), 31–50.


Abstract.  The glass beads from the Dren-Delyan necropolis are found in burial complexes dated from the end of the 6th century BC until the first half of the 4th century BC. The purpose of this study is to obtain data on the chemical composition of the glass and the technology of its production. LA-ICP-MS and SEM-EDS analyses were conducted. The analyzed glass beads are classified as a low-magnesium type (LMG), and only one of the samples is determined as high-magnesium glass (HMG). The yellow color of the glass is due to crystals of lead antimonate incorporated into the glass matrix. The green color of the beads is a result of the interaction of added copper and lead in the glass mixture, in presence of iron and chromium. Dark blue samples are colored by additives with cobalt, copper, and lower iron content. The light blue coloration of opaque glass beads is due to the high copper content, along with the presence of iron. The coloring agent of a transparent light blue bead is FeO in an amount up to 0.25 wt%. The brown color is associated with high iron content. Two different opacifiers were used for the production of opaque glass beads – antimony and tin, either individually or together. The decolorizing agent is antimony without the involvement of manganese. Based on the results of the studied glass beads, we assume at least four types of raw material mixtures for their production. A comparison of the obtained results and published data about similar ancient glass findings was made.

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