Abstract
Ganjali Khan School (Caravanserai) in Kerman is one of the prominent buildings in Kerman from the Safavid period. Valuable gypsum arrays with different techniques have been implemented in this building. Among these arrays there are the Boumsab gypsum arrays that are executed in the royal room on all sides as well as the roof of the building. One of the special features of these arrays is the color of the mortar in the layers of the lower fine coat and the upper fine coat, which can be seen in three colors: red, yellow and gray. It should be noted that in the past, a layer of gypsum plaster has been applied on the surface of gypsum arrays in this building, but fortunately, in recent years, a large part of the additional layer has been peeled off the surface of gypsum arrays. Due to being special of this architectural arrangement and have not been done any detailed scientific study on these works so far, in this article, the structure of the colored mortars of this building has been investigated. Some of the questions of this research are: What is the structure of the colored mortars of Boumsab gypsum arrays in this building? What are the Major and Minor phases of mortar composition? What was the pigment in colored mortars? In this regard, sampling was done and FTIR, EDS, XRD analyzes were performed, which along with field studies, the research questions are answered. The results of the research show that gypsum mortar with the Major phases of gypsum and anhydrite has been used in different layers. Iron oxide (goethite) was also used to color the red and yellow mortars, and ash and lime were used for the gray mortar. Also, organic materials that used to change the quality of mortar were not identified in the structure of the samples.
Keywords: Gypsum Arrays, Colored Mortar, FTIR, EDS, XRD.

Introduction
Boumsab gypsum array is one of the types of low-rise architectural arrays. In this method, abrasion of areas from the fine coat (Intonaco) surface is done in order to create a different texture between the patterns and the background, the abrasion action covers only a part of the thickness of the fine coat layer and does not reach the layers under the fine coat. This method of stucco has been common in Isfahan since the time of Shah Abbas I (Aslani, 1391: 136). Ganjali Khan School (Caravanserai) in Kerman is one of the Monument in which the high quality Boumsab gypsum array has been executed. This Monument was built at the same time as the Ganjali Khan complex in the Safavid period, and one of the most beautiful architectural spaces in terms of architectural layout is the royal room, which is decorated with a gypsum arrangement of Boumsab. One of the features of the Boumsab gypsum array in this building that makes this array one of the other Boumsab gypsum arrays that have been identified as a result of the authors’ field studies (Aliqapoo in Isfahan, Pirnia House in Nain, Aliqapoo in Qazvin, and Kalkhoran Tomb in Ardabil), is the use of colored mortar in the fine coat layers performed in the royal school of Ganjali Khan School in Kerman. In this Monument, three colors of mortar are gray, red and yellow. Due to the fact that two layers of colored substrate are used on all sides as well as the ceiling of the room, at first it seems that gypsum mosaic is of Tokhmedaravari type, but by studying it closely, it can be concluded that Bumsab gypsum array. Another point is that the Boumsab gypsum array with these properties and with three colored mortars in one space, has been studied for the first time in Iran. 

Result and Discussion
FT-IR: In the spectrum of sample R-1 (Figure 5), the index vibrations of the gypsum can be seen in 3543, 1621, 1114, 670 and 600 cm-1 (Knittle et al., 2001: 635). However, there is a noticeable structural difference in this sample compared to the western side samples. In the spectrum of this sample, absorption bands of about 713, 874, 1430, 1800 and 2516 cm-1 are observed, which are related to carbonate vibrations in the calcite structure (Ylmen & Jaglid, 2013: 121). However, in addition to the absorption bands mentioned, bands of about 469, 521 (Fe-O), 795, and about 3650 cm-1 can be seen next to the 3543 cm-1 gypsum band. These absorption bands are generally visible in the red color spectrum of iron oxides. According to the researchers, these absorption bands and their position increase the possibility of using Hormoz bole or Armenian bole in this sample (ulaiuladienė et al., 2018: 249). 
EDS: The results of EDS analysis of the samples are presented in Table 1. For the amount of sulfur obtained from the S-2 sample in this study 13.02, the amount of 16.27% calcium is required for the gypsum composition. As can be seen in Table 2, the amount of calcium is greater than the amount required for the gypsum composition. 1.7% of the excess calcium can be related to the impurity of lime in the sample, which is normal in historical monuments. Examination of samples R-1, R-2 and R-3 show a significant amount of iron. Therefore, the results indicate the possibility of using iron compounds (ochre) as a red pigment in these samples.
XRD: Two samples R-1 and R-2 were examined using XRD, the results of which are presented in Table 3 and Figure 6. The main phases of R-1 are gypsum and anhydrite, and the sub-phases are quartz, kaolinite and goethite. The R-2 sample is similar to the R-1 sample in terms of the obtained phases, except that kaolinite is one of the main phases. Usually the scratch coat (Arriccio) has added soil and sometimes ash. A small amount of goethite seems to be sufficient to create a red color in the gypsum mortar. The study of the constituent phases of the G-1 sample structure was also performed using XRD, of which gypsum and anhydrite are the main phases and quartz and kaolinite are its sub-phases.

Conclusion
In this study, sampling was performed from different layers of colored mortar and specialized studies were performed. As a result of FT-IR, it can be said that the mortar of fine coat layers are made of gypsum with low lime impurity to which some red pigment has been added at the time of curing to make the mortar red. Also, no evidence of organic matter as additives to gypsum mortar was identified. The results of EDS analysis on gypsum mortar showed the presence of a small amount of excess calcium. Also, in the red mortars of the Bottom and top fine coat layers, iron was identified as the coloring agent and the presence of red was recently confirmed. In gray mortar, the presence of ash mixed with lime is a strong possibility. XRD analysis of four selected samples showed that the predominant phase in all four cases was gypsum and anhydrite, and only in one of the samples, kaolinite was identified as the main phase. The identified sub-phases are quartz, kaolinite and goethite. So far, no research has been published on the composition of Boumsab gypsum plaster with colored mortar. It can be imagined that at first, in order to implement the gypsum array for Tokhmehdaravari, Bottom and top fine coat layers were both applied with colored mortar, and for some reason (for which we don’t know) the decision was changed. Finally, the designs are executed only on the surface layer and And has been executed in a Boumsab manner. It is noteworthy that in the same complex (in the royal porch), a Tokhmehdaravari has been executed and can be seen at present.

Abstract
Gray pottery is one of the most significant and important cultural artifacts discovered from the Bronze Age sites in the southeast of the Iranian plateau. This style of pottery has been obtained in a very large amount from the Chagardak Asr-e-Faraghi site of Chah Hashem Plain in Baluchistan, which has so far been far from the views and studies of archeology, archeology and artistic history of the southeast of the Iranian plateau. The main question of this research is about how to make and decorate these pottery. It seems that pottery making was developed in this area and they had different construction methods. The present research has been done by analytical-experimental method and based on laboratory studies. The studied objects belong to the Museum of Southeastern Iran. Measures such as documenting the condition of objects as well as sampling necessary for laboratory tests have been performed at the restoration workshop of the Museum of Southeastern Regions of Zahedan. Then, using thin section petrographic studies (OM) and instrumental analyzes with SEM-EDX and XRD methods, the data are analyzed in order to achieve the research objectives. In this study, 11 samples of gray pottery related to Chegardak area, which were obtained from emergency excavations in 2018, were performed. All pottery was wheeled and gray in dark to light and with different thicknesses but in the range of thin pottery. Archaeological studies on pottery suggest a similar composition, but show that different production methods were used. The pottery in question was pottery produced in high heat furnaces and advanced methods such that precision in construction, elegance and strength were considered by the potters. The results show that pottery in this area has been a very advanced industry that has used iron and manganese-based minerals to decorate the pottery.
Keywords:  Archeology, Petrography, Bronze Age pottery, Chegardak, SEM-EDX, XRD.

Introduction
Southeastern Iran is one of the most important and prominent regions in terms of human evolution in the Bronze Age. Evidence of this is the dispersion and existence of numerous ancient sites and hills related to the third millennium BC in this area. Significant sites such as Burnt City (Tosi, 1976; Biscione et al., 1977; Piperno & Tosi, 1975; Tosi, 1968) ¬, Bumpur (DeCardi, 1968; Mortazavi, 2004; 2006) 2018), Speedge (Heidary et al., 2019), Khorab (Stein, 1937) and Domain (Tosi, 1970) as well as Chegardak area (Heydari et al, 2015) are prominent and prominent examples in Sistan and Balochistan, all of which have been studied and various archaeological studies to date Chagardak Archaeological Site (27 ° 5’14 ‘’ N; 59 ° 7’8 ‘’ E) is located in Delgan city and Dasht-e Chah Hashem village, 10 km northeast of Chagardak village (200 km west of Iranshahr city). This area takes its name from the nearby village, namely Chagardak. This area is located in a flat and low plain. The ancient site of Chagardak in the plain of Chah Hashem Jazmourian includes a hill and two cemeteries related to the Bronze Age of Balochistan. This area has been in turmoil and damaged in 2005 due to extensive destruction and looting by traders. During the salvage excavations carried out in 1397, the Archaeological Department of the General Directorate of Cultural Heritage of Sistan and Baluchestan Province discovered a variety of artifacts, including pottery painted in pea, gray and red. Gray pottery is one of the most important finds from the lesser-known Chagardak site in Balochistan. Therefore, these findings have been analyzed and studied in this pilot study using petrographic, SEM-EDX and XRD methods. In the first stage, petrographic analysis was performed on all pottery. In the study of pottery petrography, a very important issue is the materials added to the pottery paste. All the pottery is wheeled and gray in the range of dark to light and with different thicknesses, but within the fine pottery of this region. Samples were named based on the first letter of the name of the Chagardak site in Latin (CH) and the sample number from 1 to 11. Among these specimens, numbers 1 to 8 are broken and small pieces of pottery obtained in the excavations of this area, and numbers 9 to 11 are pottery that is much more complete and with Ability to perform restoration operations (Table 1). Gray painted pottery is one of the types of pottery that has been obtained in many areas of southeastern Iran. Their designs are taken from the ecology of the region and the culture of the people of that period. Scanning electron microscopy analysis equipped with X-ray fluorescence analysis (SEM-EDX): for microscopic examination of the pottery matrix, identification of minerals as well as melting and vitrification stages of the pottery, as well as identification of the chemical composition of the matrix and minerals. SEM-EDX method was used. The SEM device used is the MIRA3 model made by Tescan, an American product. Also, to identify the composition of pigments used in painting ceramics, the EDX elemental method and the VEGA / TESCAN-XMU model made in the United States, which was coupled to the above SEM machine, have been used. The resolution was 1.5 mm at 15 kV and 4.5 nm at KV1 with BSE detector. Also, the method used in this research is point analysis. The mentioned experiment was performed in Razi Metallurgy Laboratory of Tehran. X-ray diffraction (XRD): X-ray diffraction method has been used to identify crystalline phases and mineralogical studies in the desired pottery. The model of the device used is X’spert Prompd Panytical made in the Netherlands, which has been done in Razi Metallurgical Laboratory of Tehran. The samples were analyzed at 30 Ma current and 40 Kv voltage. Information on the identification of crystal phases based on PDF2 database was reviewed and obtained by Xpert High Score Plus software version 2010. Therefore, how the art of making and recognizing the pottery industry in this region can be one of the most important questions and goals. Therefore, in this research, we have tried to answer some questions such as the following questions by using some common methods of analysis in the archeology of ancient pottery. A) What kind of mineralogical composition does the pottery discovered from Chegardak have? B) Structural and archaeometric studies of ceramics show what kind of process shows in the way of making and baking pottery?

Conclusion
These experiments showed that the pottery has a very dense, hard and non-porous texture, which shows that the prehistoric potters of the Chagardak area five thousand years ago were very precise and skilled in the type of drilling and processing method. So that no emptiness or signs of improper weaving can be found in the pottery. This point should be considered as one of the most important features of gray pottery in this region, especially in the southeast of Iran. On the other hand, the resulting studies show that the soil used in the manufacture and production of pottery paste is very desirable, washed and free of any additives. As their strength is so high after firing that they can not be easily broken, this can be seen well in the type of sintered and semi-glass texture of pottery. Also in XRD phase analysis, the presence of high heat phases was detected. It is very likely that high heat furnaces using regenerative conditions were used in the construction of the pottery. On the other hand, in the archeological excavations and emergency excavations carried out by the archeological group of the area under the supervision of Mohammad Heydari, the architectural remains of a pottery kiln, molten pottery and kiln were discovered, which shows this. This industry has been an art and native production of the people of this area. The last stage of producing a pottery was the methods of polishing and decorating it to produce a magnificent work of art. Elemental studies showed that the prehistoric painter and craftsman of Chagardak used iron-based minerals such as hematite and red recently to record red colors, and a combination of iron-oxide and manganese-based materials to produce black and dark colors.