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
Among the architectural arrays of Imamzadeh Hossein in Qazvin that can provide valuable information to researchers, are the remaining parts of the murals. Considering that Qazvin was the capital during the second period of Safavid rule, the study of Safavid and Qajar period buildings in this city can be of great importance. Compared to the existing historical monuments, few studies have been done on the technical knowledge of the layers of historical murals.In the present study, the identification and recognition of pigments related to the remaining murals of this monument and gilded layers has been considered. Also, in order to complete the technical information of the murals, the mortar of the fine coat (finishing plaster) and scratch coat (levelling coat) under the paint has been studied in terms of structure and chemical composition. To identify the pigments used in the murals as well as the materials used in the mortar of the underlying layers of the mural and the floor mortar, the hydraulic properties and the mineral and chemical composition of the mortar from X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy and digital microscope have been used. As a result of the studies, it was found that the Pastiglia in the murals is made of a mixture of gypsum and Bole (Armenian Bole, Hormoz Bole). Apply a white Primary layer on the pastiglia on which the gold leaf is applied with low copper impurity. In this murals, three types of gold sheets have been executed. Green: A mixture of arsenic pigment with azure blue and Prussian blue; Green-blue: a mixture of green earth pigment (Celadonite) with white lithopone; Blue: a mixture of azure and Prussian blue pigments with White lead; Red: A mixture of ocher red and orange arsenic; Primary layer filler: a mixture of Huntite and White lead; black: It is a mixture of cobalt black and iron black. The structure and composition of mortars were also identified.
Keywords: Mural, Pigment, Gilding, Structural Study, Mortar, Qazvin.

Introduction
The technical diversity of murals in the Safavid and Qajar periods is one of the important issues of knowing historical murals. To technical understanding historical mural, its different layers are subjected to careful scientific study. The main layer is the color layer which consists of two parts: dye and binder. It should be noted that the array of gilding in the mural and the borders of the mural is also considered as a mural. Imamzadeh Hossein is one of the prominent buildings of Qazvin city. Most of the murals of this building belong to the Qajar period. Evidence shows that traces of the Safavid periodare also left in this building in the lower layers.
The aim of the current research is to obtain technical information about the layers of murals of this historical building. Identifying and recognizing the pigments in historical murals from archeology point of view helps completing the technical information about the use of pigments by artists. Some pigments have a specific starting date, which helps clarify the date of making the murals.
In archeology, studies have been conducted regarding the technical knowledge of different layers of historical murals in Iran, but very few studies have been done considering the volume of murals in Iran in different periods. Therefore, it is necessary to more complete these studies over time which its result is to complete the database in this field. In the upcoming research, in order to know more about the murals, technological studies were done on it. After field studies, the pigments used in the murals were sampled and identified. To complete the information, the lining layers and the substrate and a sample of the floor mortar were also studied. In this regard, the main questions of the current research are: What pigments are used in the murals of Imamzadeh Hossein in Qazvin? What method was used for gilding in these murals? What are the physical and structural characteristics of the lining layers and substrate of the studied murals?

Discussion in the Results and Findings
a. Scanning Electron Microscope: In the sample (2021.Q.IH.1) there is a large accumulation of gypsum crystals and intertwining has been created between them. The empty space between the crystals is little and also the crystals are irregularly placed together at different angles. In 2021.Q.IH.10 sample, needle- shaped gypsum crystals that are intertwined can be seen in many parts. In 2021.Q.IH.11 sample, gypsum crystals in different sizes are placed at different angles. In this sample, there is no long needle crystal and instead, the crystals have grown a lot in the width direction. In 2021.Q.IH.12 sample, the gypsum crystals are slightly different in terms of shape from the samples of the floor and lining layer.
b. Energy-dispersive X-ray spectroscopy (EDX): In 2021.Q.IH.1 sample, there is a small amount of silicon, aluminum and magnesium, which is related to soil. In 2021.Q.IH.2 sample, the amount of sulfur is about 13% which some part of it is related to yellow pigment and some part is related to blue pigment. In 2021.Q.IH.3 sample, elements of potassium, aluminum, iron, magnesium and silicon can be seen next to oxygen. These elements are related to Verona green or green earth pigment. In 2021.Q.IH.5 sample, a high percentage of gold and a relatively low percentage of copper were detected in the sample. In 2021.Q.IH.6 sample, two coloring elements, iron and arsenic, along with sulfur have been detected. In 2021.Q.IH.7 sample, the main filling material is huntite or chalk. On the other hand, a small amount of lead has been detected in this sample. Gold, copper and iron have been detected in 2021.Q.IH.8 sample. In 2021.Q.IH.9 sample, two elements, cobalt and iron, along with sulfur, are significant and influential elements in making black color. In 2021.Q.IH.10 sample, the highest percentage of elements is related to calcium and sulfur. In 2021.Q.IH.11 sample, except the main elements of gypsum, a very small amount of elements of silicon, aluminum and magnesium have also been detected.
c. X-ray diffraction spectroscopy: As a result of the phase analysis of 2021.Q.IH.1 sample which is related to the lay-up under the gold sheet, quartz has been detected. The quartz detected in the lay-up is related to the red flower (Armenian flower) that was added to the plaster during the mortar processing. The next identified phase is gypsum. As a result of the phase analysis of 2021.Q.IH.10 sample which is related to the floor coating mortar, quartz has been detected. The next identified phase is gypsum. As a result of the phase analysis of 2021.Q.IH.11 sample, which is related to the floor coating mortar, anhydrite phase has been detected in the studied sample. The amount of anhydrite in the lining layer is higher than gypsum. As a result of phase analysis of 2021.Q.IH.12 sample, which is related to the substrate layer in the studied mural, quartz has been detected. The granularity of the quartz phase in the substrate was much finer than the previous samples. The next identified phase is gypsum.

Conclusion
The lay-up used in the murals of this building is made of a mixture of plaster and red flower (Armenian flower, Hormoz flower). Green color is a mixture of arsenic pigment with lapis lazuli and Prussian blue. Blue-green color is a mixture of green earth pigment with lithopone white. The blue color is a mixture of lapis lazuli and Prussian blue pigment along with white lead. The golden color of embossing is gold sheet with a small amount of copper impurity. The layer that is applied on the lay-up is also a gold sheet with a small impurity of copper. In line with the studies on the shiny brown sample, it was concluded that this layer is a gold sheet with copper and iron impurities, which its surface has corroded and darkened over time. In fact, three types of gold sheets have been used in the studied murals that two of them are similar and seem to belong to the same period. A layer that is different in terms of the composition of elements and impurities belongs to later periods. The red color in these murals is a mixture of red ocher and orange arsenic. The white color filling the preparatory layer is a mixture of huntite and white lead. Black color of embossing is a mixture of cobalt black and iron black. Contrary to imagination, the floor mortar is a gypsum mortar with two phases of gypsum and anhydrite to which some sand and soil have been added. Due to proper processing, this mortar has adequate strength, although humidity has caused damage to the work over time. The lining layer and the substrate in the studied murals are made of plaster mortar. There is a difference that the thickness of the lining layer is greater than that of the substrate and it has coarser graining and more impurity. On the other hand, the looser mortar of the substrate is due to the way of processing, and the arrangement of gypsum crystals is different from that of the lining layer.

Abstract
This article discusses the structural analysis of ancient mortars used in Ojai’s Castle, which belongs to the Ilkhanid period in Bostanabad County, East Azerbaijan Province. Various methods, including field studies for documentation, sampling, and laboratory analysis using X-ray diffraction (XRD) and X-ray fluorescence (XRF), were utilized to investigate the structural and physicochemical properties of the ancient mortars. For this purpose, ten mortar samples were collected from different sections of the outer walls of the castle, which were excavated in the past five years, and their dominant phases and compositions were identified using XRD and XRF. The results show that the composition of the mortars used in the castle is significantly similar. Contrary to existing assumptions based on the use of lime-based mortars in cold regions and stone structures, the mortars in Ojan Castle are composed of gypsum and quartz-based high-purity gypsum mortars. These mortars were used for structural reinforcement and, especially, for enhancing their compressive strength. Based on these findings, this study can serve as a reference for future research on the structural analysis of ancient mortars to restore the castle.
Keywords: Characterization, Seljuks-Ilkhanid, Ojan Castle, Mortar, XRD, XRF.

Introduction
Historical architecture exemplifies the dynamic progression and development of knowledge, structure, recognition, and production of diverse materials. Mortars, as significant architectural elements, play a crucial role in this evolution. Remarkably, numerous mortars have retained their structural attributes for centuries. These historical mortars represent cultural accomplishments, exhibiting distinct properties influenced by raw materials, technological methods, and their manufacturing and utilization processes. The analysis of historical mortar’s composition serves as a valuable tool in understanding the construction techniques and technological advancements employed in the past. By studying the structure, composition, and processing methods of traditional mortars, we can make informed decisions regarding their conservation, restoration, reproduction, and identification of potentially damaging factors in historical buildings. Furthermore, mineralogical and chemical analysis of mortars provides essential insights into their setting characteristics, mineral grading, and compound quantities, offering a comprehensive understanding of their properties. Concerning the specific topic of this research, which is related to the historical and cultural mortars of the Seljuk-Ilkhanid era we can say undoubtedly, the Ilkhanid era can be considered one of the brilliant periods in the history of urban planning in Iran and another beginning in the emergence of a new style in creating and developing urban spaces. This style, which is known as the “Azeri style”, hastened the creation of royal cities such as Ghazaniyeh and Soltanieh and the strategic mother city of Tabriz, which is the manifestation of the ideals and urban planning ideas of the Mughal Ilkhanid. It has remained unstudied until today. In this research, the structural analysis and identification of the mortar composition of the historical castle of Ojan (figure1-3), related to the Seljuk-Ilkhanate period, will be examined and studied. Until now, five seasons of scientific archeological excavations have been carried out in the historical castle of Ojan from 2018 to 2022, and the results show remarkable stone architecture and architectural decoration such as Muqarnas made by gypsum, tiles, shaped stones, and various objects. Belongings include copper coins, pieces of pottery from the Seljuk-Ilkhanate period, glass, metal nails, etc. (figure4-7 & table 1) 
The most important research questions regarding the mortars used in Ojan Castle are: 1. What types of mortars are present in Ojan Ilkhanate castle? 2. What are the fundamental characteristics of the mortar used in Ojan Castle? The research methodology for this study consists of three main components:  1. Gathering documentary information through library studies. 2. Conducted field studies, including sampling from the historic Ojan Castle and documenting the current condition of the site to understand the nature of the building under investigation. 3. Performed laboratory studies, specifically analyzing samples taken from the outer wall of the castle. This analysis includes structural analysis and qualitative examination of mortar materials.

Materials and Methods
In this study, after examining the explored sections of the Ojan castle, mapping of the structure was carried out. Based on the current condition of the walls and the materials used in the construction (Fig. 8), 10 random representative samples were taken from different sections of the castle, including the outer parts of the main walls and the areas between the main materials. The samples were selected from different parts of the walls to ensure sufficient dispersion. The sampling method involved separating layers from both intact and deteriorated sections. Fig. 9 and indicates the locations where the samples were taken. Based on field observations, the mortar layers, especially in shallower and more exposed areas, had weak and powdery structural conditions. However, at depths greater than 20mm from the wall surface, the mortar exhibited better strength compared to the surface layers. The color of the mortar was mostly white, with some areas having a slight grayish tint, and no traces of plant remains or other components were observed. In the next stage, images and visual information related to each sample were recorded on-site. Descriptions of the visual characteristics of the samples, along with images and sampling locations, were collected and documented in Table 2. All samples were powdered and passed through a 200-mesh sieve. They were then barcoded and sent to the laboratory for XRF (table 3, 4, figure10) and XRD (table 5, Fig. 11) analysis. The samples were barcoded using the following format: “Ojan Castle, 2020 (OC20), Tranche number (T), Sample code (S)”. For example, a sample would be labeled OC20-T16S01.

Discussion 
With the aim of structural analysis of the mortar used in the stone walls of Ojan Castle belonging to the Seljuk-Ilkhanate historical period in Bostanabad city, 10 samples of mortar were selected from different parts of the outer walls. Based on the results of the experiments (XRD, XRF), the use of mortar with the leading and dominant phase of gypsum is used in all samples, and also all types of phases with silicate structure and phases in the soil can be seen in all samples. To construct this mortar, high-purity gypsum and sand were used. Approximately %8 of the mortar composition consisted of other components, mainly soil elements such as Muscovite, Albite, Salts, etc. The presence of these materials and phases is natural due to the inherent porosity of gypsum mortar and the fact that this architectural structure has been buried in the soil for several centuries.

Conclusion 
The use of semi-fired, semi-pounded gypsum, with the addition of sand as an intermediate mortar between stones, as well as for pointing in various sections of the outer walls of Ojan Castle, indicates the use of processed gypsum mortar in cold regions such as Bostanabad in the northwest of the country. As we know, in the field of conservation and restoration of historical architecture, the use of authentic materials that correspond to the original substance is crucial for preserving the authenticity, historical value, and cultural significance of ancient artifacts.
Based on this principle, the use of traditionally processed gypsum for constructing traditional mortar in the conservation of this ancient site can be considered significant in terms of maintaining authenticity. Considering recent seasons of excavation and access inside the castle, conducting similar tests on samples of interior plaster can reveal the differences between the mortars used on the outer and inner surfaces. This information can provide insights for proposing restoration and conservation procedures for the site.