A Resarch on Tubular Glass Rods of Untash-Napirisha Doors and Their Analysis by X-Rey Fluorescence Method

In the excavation of Al-Untash-Napirisha (The Site known as Chogha Zanbil), tubular glass rods were found. However, so far, no comprehensive research has been conducted about them in the form of an investigational article and only constituent elements of a few glass pieces which had been entered the Corning Museum of Glass in New York have been analyzed and determined. In the excavation done by Roland de Mecquenem and Michaleon in the years between 1935-1939 AD and 1946 AD in this site, many tubular glass rods, weighting almost 100 kg, had been discovered. In the description of these findings, it was assumed that they were long glass beads in dark blue and white or amber color with lengths of 20 to 28 cm. that in some of them bronze rods had remained. After World War II, between1951 to 1962 and during the excavations done by a French group in Ziggurat by Roman Ghirshman, pieces of wooden doors with bronze rods in them had been discovered. With the development of human knowledge today and the engineering science applied to archeology, a discipline referred to as archaeometry has been formed. The results of analyzing a single sample kept in storages of Susa Castle by conducting fluorescence x-ray method in laboratory of faculty of science in Tarbiat Modarres University, in comparison with the results of this same analysis on four samples done in Corning Museum of Glass shows that Elamite glassworkers produced these glass rods with a specific goal in their minds. The combination of various materials results in the production of blue and purple to black color glass. For instance, if copper oxide is mixed with potassium and sodium, a color spectrum of turquoise blue is created. The second and most important reason of creation of this blue color is the combination of Fe2O3 with the sulfur existing in the plant ash, creating a spectrum of blue color. Generally, the Elamite glassworkers were familiar with the features of the pigments and materials, also, they could be used to degree of amount of the raw materials in Choghazanbil glass rods to make them, so These glass tubes were more resistant because being used in the door of temples proves. The hypothesis that in the glass working sites of Choghazanbil, elites familiar with the knowledge of materials were employed for supervision and the same supervision systems were used.
Keywords: Chogha Zanbil, Tubular Glass Rods, 13^th Century B.C. (Middle Elamite Period), XRF.
 
Research Questions
How and in what ways the glass rods have entered the museums and collections? What techniques are involved in the production of these materials? Can, based on ancient studies, the production of these glasses be considered as systematic? Are the results obtained from sample under study consistent with those from Corning samples? Has any change occurred in the compounds or production of these glass rods, considering their application (in order to decorate the doors of the temples)? Has the source of the constituent materials of these glasses been the same? Have they been made based on the same instructions?
 
Research Methodology
The present research study has used two data gathering methods. First, using library studies and published research reports. Second, archeological studies conducted on a sample from Susa castle warehouses, using the laboratory method of X-ray fluorescence with Philips PW2404 software in the laboratory of the faculty of science in the Tarbiat Modares University. Then, the data related to the sample under study and four Corning samples were analyzed by ABM Spss 25 software, providing outputs in the form of diagrams, based on the required data. Although these tubular glasses were found in the entrance of buildings so-called North-eastern, they could not understand for what they were being used. Along with these tubular glass rods, copper sheets identified as part of these doors had also been found.
 
The Method of Producing the Glass Rods
The rods made of semitransparent glasses with dark blue purplish color, that a wide band of white glass has been wrapped around each, have been used in the wooden double doors of some of the chapels and Zigurat Al-Untash- Napirish. These rods were produced with rod frames in which a bronze rod played the role of the frame and in some of them, these bronze rods remained. In this method, to make the rods, some melted liquid is taken with a metal rod and, then, as the result of rolling this melted liquid on a surface, it is formed as a rod. Then, a rather thick layer of glass with white color is wrapped and twisted around this warm, already- made rod. Later on, it is rolled on a flat surface so that the added layer of glass is widened and absorbed by the main body and is formed as a helix band.
 
Conclusion
The glass rods of Choghazanbil known as the oldest and most ancient glass pane in the world are of significant importance in the history of glasswork and due to this same reason, they have found their way to the various museums of the world. The glass rods used for the decoration of the doors of the temples in Elam. The existence of bronze rods used as frames inside some of the glasses in the place of excavation indicates that it has been probably produced in a site near Choghazanbil. Moreover, the results obtained from the evaluation of the sample under study with the X-ray fluorescent method and its comparison with four Corning samples studied and experimented by Brill shows that Elamite glassworkers produced these glass rods with a specific goal in their minds. The high amount of calcium in these rods shows that they intended to make glasses with higher strength and resistance as these rods were used for the doors of temples and, consequently, they had to be more resistant than the usual glasses. The evaluation of weight changes of magnesium oxide to potassium showed that the source of supplying the soda of these glasses has been the ashes produced from the plants grown in the salty soils. Increase or decrease in the amount of the metal oxides as color elements can lead to color change and the creation of different color shades. One of the characteristics of metal oxides in the primary compound of the glass is that through minimum change in the metal oxides, different color spectrums are created. However, the blue color in the glass rods of the Choghazanbil has two main reasons: First, if copper oxide is mixed with potassium and sodium, a color spectrum of turquoise blue is created. The second and most important reason of creation of this blue color is the combination of Fe2O3 with the sulfur existing in the plant ash, creating a spectrum of blue color. The degree and amount of the raw materials in Choghazanbil glass rods is an indication of the same instructions and supervision on the production of these glasses by the experts and masters in the Choghazanbil temple in the 13th century B.C.