The Study of Buff Color and Red Potteries’ Structure in Shahr-e-Sokhta Site in Sistan

Abstract
The Shahr-e-sokhta of the third millennium BC has always been of interest to archaeologists, and much research has been done on the site. The objects discovered from this Bronze Age site are more important to researchers than the site itself, especially the pottery, which is the most abundant. Among the countless pottery discovered in the site, 12 pottery pieces, including 8 buff color and 4 red color pieces, were selected for research, all of which are small pottery discovered from the cemetery and have ritual uses. Due to the low frequency of red color pieces, the hypothesis that these pieces of pottery is imported is hypothesized. Among the set goals, we can mention the similarities and differences in the manufacturing technique, the study and comparison of mineralogy, as well as the structural comparison, the constituent phases and the cooking temperatures in the furnace. Archaeological analysis and X-ray diffraction were performed by powder method to achieve the objectives and studies on the studied samples. Analyzing the obtained results, it was found that the samples of the studied pottery were similar in terms of their constituent components and constituent structure, and the region’s siliceous mineral templates, such as naphtha, were used. The main difference in the composition of the dough was the high percentage of each of the minerals in the pottery dough, the method of making and the way the dough was processed by the potters of the Shahr-e-sokhta. Studies have shown that the constituent texture of these pieces of pottery is in two types, micro-bleeding and large-flora, but the minerals and fillers in their constituent structure are not very different from each other. Also, the furnace temperature played an important role in determining the color of the studied samples, and in the samples where the calcite mineral was present, the cooking temperature was below 800. C and the non-calcite samples were cooked above this temperature. According to the results of experiments and analyzes, it seems that the potters of the Shahr-e-sokhta had achieved the technology and method of making pottery of the red spectrum.
Keywords: The Shahr-e-Sokhta, Red and Buff Color Pottery, Archeology, Petrography, X-ray Diffraction.
 
Introduction
Different cultural objects and spatially founded potteries in ancient sites are one of most important hand-mades and moost valuable resources that lead us to recognize ancient periods. Potteries and clay objects specially are evidences of changes in their style and technic in progresses of their owner’s life development and livelihoods according to their high resistance against erosion and corruption during centuries and are indicatives of different manufacture styles of pre-historic craftmen and are valuable for researchers in different scopes such as archeologists, restorers and anthropologist (griffits, 1999). On of ancient sites which was developed in this industry in Bronze Age is ancient site of Shahr-e-Sokhta located in Sistan and Baluchestanprovince. thousand founded musicological, laboratory and study objects are evidence of richness and welfare of people of this area. Those objects confirm relationship between this city and countryside’s which were provider’s requirements and also confirms relationship between this city and far away cities for good exchanges. These objects are made of materials such: clay, wood and planet, different stones, metal, bone and etc… clay is one of essential and primitive material to manufacture in this society and were produced wonderfully, so nowadays you cannot cross street without tread on potteries. Actual workshops of pottery production were in countryside’s and most knowns of them are seen in riverside.  hills and are related to second period of lodge ment in Shahr-e-Sokhta (Scalone, 1394: 228). Founded potteries in this site contain potteries with colour spectrum from buff color, red and gray in very different shapes, froms and designs. This study is according to review of samples of buff color and red potteries found in Shahr-e-Sokhta is used to study on similarities and differences between technic of manufacture and pottery (mineralogy and solid used in pottery dough, baking temperature in kiln and etc…) and comparison this sample in term of structure and former phases. After review and mineralogical comparison by laboratory- machinery technics and analysis the results, we want to follow purpose of study and also we try to find the answer of are potteries imporred or native and this is explaind clearly in the following.
Intruducing Samples
According to defined porpuses, 12 pottery objects are choosed between what are founded during methodical archeological excavations in Shahr-e-Sokhta.This objects are broken and unrestired and are 7 buff color and5 red potteries were able to sampling and experiment. Some of them are designed by black and brown colors. discssion about results of carried out analyzes analysis of results of petrography of thin section (microscopy). In general, potteries contains two portion: dough (base) and filler in petrographical studies on potteris, important discussion is about element in this case. Some of samples hascalcit and some of them are calcit-free cany of calcit or canies with carbonate fondantion destroyed in temperature of 800 centigrades degree. Loss of calcit in studing potteries show that used temperature for those potteries are more than 800 centigrades degree (Emami,.2010, Ramos et al, 2002).
 
Analyze of X-Ray Diffraction Analysis
XRD analyze done on 3 samples of red potteries and 3 samples of buff color potteries. Quartez founded phase is one of obvious phases in spectrum of both red and buff color potteries. This phase shows that potteries baking was in oxidation condition of kiln. In this condition temperature doesn’t grow up more than 800 cenligrade degree and this case is clearly seen in microscopic studies of potteries. Calcit phase isn’t recognized in other potteries that shows temperature for baking this pottery was more than 800 centigrade degree, it’s because calcit will be destroyed in temperature more than 800 centigrade degree as it has noticed before.
 
Conclusion
Studied potteries are similar in terms of materials and structure and main difference between them is in combination and frequency percentage of their componentsindough. temperature of kiln and oxidation or resuscitation condition is important factor for determination of colour of potteries. Size of founded pieces in dough of porphyry-texture potteries doesn’t exceed 1 milimeterand the most existing combination in dough is quartezcany and pieces of nibbler that their resources is founded in stones of this area frequently (Agha nabati, 1383). According to ecological maps Zabol (1:1000000 and 1:250000) studied area is located in a flat that is created by anaphylactic sediments and deposits of Hamoon lake. In this region you can find different types of stones such as sand stone, fossilizedGrivna limestone, cryptocrystalline silicone stones like nibbler and philattropist and etc…). (Geodogical survey of Iran, 1385) after comparison of structure of studied potteries and structure of other studied potteries Shahr-e-Sokhtawe can demons trate that these potteries are native and related to industry of Shahr-e-Sokhta pottery.