The Chemical Composition And Manufacture Process Of The Glass Beads Excavated From Shirenzigou Sites In Balikun County,Xinjiang

Barkol county located in the Kumul Prefecture of eastern Xinjiang which is the junction point connecting central China and northern Xinjiang, Shirenzigou sites in the Balikun county was a great nomadic tribes settlement in the eastern Tianshan Mountains. The glass beads excavated from the tomb of MO 11 in the Shirenzigou site and the tomb of M1 in the Xigou site, date between the late Warring States to the early West Han dynasty (3rd century B.C-1st century B.C). To understand the chemical compositions and manufacture process of these glass beads, the samples were analyzed through the examination of LA-ICP-AES, EDXRF, LRS and 3D optical microscope. Afterwards the test data were processed through the principle component analysis (PCA) and other multivariate statistic analysis methods. Based on these results, the provenance and weathering mechanism of these glass beads will be discussed. Finally, we gain the correlative information between Shirenzigou site and Xigou site. Main conclusions are shown as following:(1)The chemical compositions:the glass beads from the Xigou site were all Na2O-CaO-SiO2 system, the plant ash were used as flux, the lead antimonite were used as opacifying agents of seven green glass beads, the main colorant are copper and cobalt. Meanwhile, the glass beads from the Shirenzigou site were PbO-BaO-SiO2 system, the lead were used as flux, the main colorant are copper and iron.(2)The manufacture process:the glass beads (include the basis body of compound eye beads) from Shirenzigou site were manufactured by molding method, the mosaic way of these eye beads were embed by stratified. Meanwhile, the glass beads from Xigou site were manufactured by winding technique.(3)In addition, Based on the chemical compositions, the weathering mechanism of these glass beads were discussed. The result shows the weathering area and fresh area of these glass beads from Shirenzigou site and Xigou site have different characteristics. In the weathering process, the glass beads from Xigou site were accompanied by the loss of the alkali elements such as sodium and potassium, while the glass beads from Shirenzigou site were accompanied by the accumulation of lead and barium on the weathering surface.(4) Compared with the contemporaneous glass beads, the result illustrated that the chemical composition of glass beads from the Xigou site were different from the western Na2O-CaO-SiO2 glass beads, it was highly plausible that the glass beads were manufactured in the central Asia or Xinjiang region; while the chemical composition of glass beads from the Shirenzigou site were relatively centralized, which shows they were manufactured from the same place, the glass beads from the Shirenzigou site were imported from the central region of China. The study confirmed that the Balikun was an important place for the communication of material culture between the East and the West, meanwhile the nomadic people played a significant role for the spread and communication of glass beads.