Abstract
Due to the extent of the empire’s territory, the remains of the Achaemenid stone pillars have been registered in different parts of Iran. The remains of this architectural style can be seen in the monumental set of Pasargadae, Persepolis., Naqsh-e Rostam, Lidoma and Tomb-e Bot in Fars Province, the remains of Shush in Khuzestan Province, and stone works of Ecbatana in Hamedan, Rivi Palace in Northern Khorasan Province, and Achaemenid palaces in Borazjan region in Bushehr province. The rock mining of these monuments was recognized as local. However, in Boushehr Province, two ancient mines of Pouzepalangi Rahdar and Tang-e Gir of Borazjan Region have been named. The maximum extraction and application of the crème color stones from the Puze- Palangi mine were registered from the palaces of the Borazjan Region. However, for the geological structure of the black-gray stone of Acamenian palace in Charkhab of Borazjan, samples of this type of stone were extracted from Charkhab palace. These samples were compared with the gray-black samples of the Bardak-e Siah and Sang-e Siah Palaces of Borazjan. With the petrographic studies of thin sections obtained from the palaces and chemical analysis of XRD and XRF, the structural process of the gray-black samples of the Achaemenid palaces of the Borazjan region entered a new stage. The results of the petrography studies indicate that the gray-black stone samples of Charkhab palace corresponded to the sample of Sang-e Siah Palace and Badak-e Siah, considering the microsprite and sprite background, and the few amount micrite as well as the layered structure. Also, the analysis of the analytical samples of XRD and CRF of these stones indicates that the samples of Charkhab Palance and Sang-e Siah are the same. Given that no trace was found in the mining for the gray-black stones in Boushehr Province so far, it can be then claimed that these stones were extracted from a non-local mine. 
Keywords: Borazjan, Charkhab Palace, Bardak-e Siah Palace, Sang-e Siah Palace, Petrography, XRD, XRF.

Introduction
The coasts of the Persian Gulf, especially the ports of Bushehr and Borazjan in the golden age of Elam, i.e., the late 2nd millennium BC, has been one of the important centers of trade and the interface between the sea route of Shush and India. The fertile and tropical areas of Dashtestan were among the areas where the Achaemenid dominated shores and benefited from the proximity to the sea. They provided places for themselves in these areas so that they could spend the winter there. The building of Charkhab Palace in Borazjan is known as the winter palace of Achaemenid Cyrus due to its great similarity with the private palace of Cyrus in Pasargadae.
Research Questions and Hypotheses: The main questions of research are as follows: What is the structure of black-gray stones used in the Achaemenid architecture of Borazjan palaces? What is the structural relationship between black-gray stone in the Achaemenid palaces of Borazjan (Charkhab, Bardak-e Siah and Sang-e Siah)? Based on current studies, what opinion can be expressed about the mines of Borazjan Achaemenid palaces?
Research Method: Petrography and analytical methods of XRF and XRF were used to the geological structure of the gray-black stones of the stone pillars of Charkhab Palace in Borazjan. In the meantime, using the research method thin-walled structure to observe the minerals and adopting the samples were done with the OLYMPUS BX51 polarizing light transmission microscope, made in Japan, with the capability of filtering light in the XPL mode of the analyzer and emitting polarized light. XRD experiments to identify and detect the crystalline phases forming in the study samples and qualitative and semi-quantitative determination of crystals by powder method (with Cu) target radiation lamp with a maximum potential difference of 40 KV and maximum current intensity of 30 mA, fixed sample and Needle detector) was performed on three samples of historical palace stones in Bim Gostar Taban laboratory in Tehran. The results were analyzed by High Score Plus software. XRF experiments were performed to identify and quantify the constituent elements of study samples of Achaemenid palaces by powder method and with the model device: PW1410 Manufactured by PHILIPS Netherlands in Bim Gostar Taban laboratory in Tehran on the same three samples.

Research Background 
Borazjan city is located 67 km from Bushehr and 226 km from Shiraz. Due to the discovery of a piece of a stone pillar base when digging a water canal in Borazjan in 9171, the General Directorate of Archaeological Research of Iran assigned Dr. Ali Akbar Sarfaraz to explore the site in which this work was discovered.  Dr.Ali Akbar Sarafraz was the head of the Iranian Archaeological Board in Bishapour at that time. Therefore, archeological operations began in this ancient area, and at the end of the one season of the excavation, the main form and structure of the columned hall were manifested. In a study entitled “Spatial analysis of the Achaemenid palaces in Borazjan” the appearance, location, and objects obtained from these sites have been discussed.

Petrography Results 
The gray-black stone of all three Achaemenid palaces of Charkhab (CH1, CH2, and CH3), Bardak-e Siah (BS1), and Sang-e Siag of Borazjan (SS1) are calcareous and boiled in contact with 0.1 normal hydrochloric acids. These carbonate rocks have a microsparite texture to sparite, and are micrite to a small amount, and have few quartz grains.

XRD Analysis of Gray-Black Stone Samples of Achaemenid Palaces in Borazjan Region 
The spectrum of gray-black stones of the Achaemenid palaces of the Borazjan region, which includes the samples of Charkhab Borazjan (CH3), Bardak-e-Siah (BS1), and Sang-e-Siah (SS1), the matching of the spectra of the same limestone is observed. However, based on the peak intensity of calcite in the samples of Charkhab Palace (CH3) and Sang-e Siah (SS1), which shows 11000, are placed in one group. Also, the sample (BS1) with a peak intensity of calcite over 14000 is observed separated from the group.

XRF Analysis 
In the analysis of the black-grey stones of the Achaemenid palaces, the sample of grey-black stones of palaces has been compared as only the samples of palaces are available. Also, the possible mine of the black-grey stones has not been reported in Boushher Province so far. Accordingly, the oxide of the main elements, such as SiO2, CaO, P2O5, TiO2, and MgO, represents particular values in the table. These values are approximately close to each other in the sample of the grey-black stones of the Achaemenid palaces. Therefore, they are considered an appropriate indicator of similarity. Graphs of oxide values of SiO2, P2O5, TiO2, CaO, and MgO of the samples are consistent. Also, the accordance of the oxide values of the mentioned elements, the values of the secondary elements (in terms of ppm) of the gray-black stones of Charkhab (CH3), Bardak-e Siah (BS1), and Sang-e Siah (SS1) rocks are observed.

Analysis and Discussion  
Using the laboratory and scientific methods and comparing the results of this paper with the results of the papers on Pasargadae and Persepolis, the relationship between the sources of extraction of gray-black stones of the complex of Achaemenid monuments in Borazjan Region of the Fars province mines, Majdabad mountain mine in particular, around the Perspolis and Sarpaniran and Ahmadbegi Mines in Pasargadae is rejected. The presence of several large pieces carved from this type of stone in the east of the Achaemenid palace of Charkhab Borazjan confirms that Charkhab palace was in the process of construction. However, these stones which have been left on the ground two hundred meters east of the palace, are reasons for the existence of a stone-cutting workshop of Charkhab palace or another building that has not been excavated yet.

Conclusion 
Studies on the gray-black rocks of Achaemenid palaces show that mining traces or mine exposure of this kind of stone have not been seen or reported in the region. Therefore, it seems that these mines were not local, and the stones were supplied from other sources. Also, the hypothesis based on that the grey-black stone mines might have been local depends on the more extensive field studies in the future.

Abstract
Using laboratory of XRD & XRF, this research project was performed to identify the component of the pottery related to Seleucid/ early Parthian period. In excavations performed in western Iran, a number of Seleucid & Parthian site were identified, regarding shape and technical formatting roughly homogenous pottery pieces were found. It could not exactly be determined how many of the discovered pottery pieces of the Seleucid/ Parthian period’s -whether found from surface or stratigraphy excavations- had a regional origin. Determining their homogeneity which was solely based on external similarities and typology has given rise to possibilities of widespread trading of pottery or major centers of production. The main problems in research include How was the selection of consumables for the production of stained glassware in western Iran in two periods of Seleucid and Parthian? How can one know about the similarity and difference between the soil elements and the percentage of pottery and logic soil, whether they are indigenous or imported? Despite the apparent similarities, is the conditions and technique of pottery baking types in the western region in two periods, or has it changed with the evolution of governance in the fabric of pottery? This research is qualitative and has a descriptive-analytical nature. The research method in this paper is a combination of archaeological field activities, laboratory studies, and librarian compilation. Awareness of the explorations carried out in the Seleucid-Parthian sites of the western part of Iran, as well as mineralogical studies based on library information. However, as no archaeological evidence has been found to indicate the existence of such centers, such hypotheses could not be considered. The XRD & XRF methods were used to study the building elements in the excavated pottery samples. Using these methods, the similarities and differences between the clay used in making Seleucid & Parthian period’s pottery and the clay found in the region were studied. Ten sample pieces collected from Delfan, Alashtar, and Nahavand regions, were studies. The samples were selected from archaeological site of Chogha Taghi, Pat-Koole, Zarin Deh Sefid tepe, Hassanabad Sanjabi, Cheshme-Kaboud tepe, Aliabad, Molaghala Adlabad, Shaelie (Shahian), and Laodicea. The 10-pottery sherd often have a bright red peppermint, a dense bubbled glaze, a soft mineral mixture, and geometric paintings and images of birds and animals that are painted in brown and black. The shape of the dishes often shows small bowls and small cups that are well polished and polished and cooked at a proper temperature. However, as these methods usually because a great damage and in most cases destroy the samples, smaller and less important pieces which had these componential characteristics were used. The results of this study indicates that, matching the raw materials of the pottery with the geological structure of the region, it can be noted that the pottery was produced in the studied area. Also, the type, technique, and their baking technique from pottery are similar to each other and confirm that its local production and it dismisses the change in the production process or the non-localization of the production of clay crowns during the Seleucid period.. 
Keywords: Seleucid Period’s, Parthian Period’s, Pottery, XRD, XRF, Western Iran.

Introduction
Our recognition of the western Iran Seleucid/ early Parthian painted pottery is so little in limited due to so many various reasons. The potteries as such are painted and fragile and belong to Seleucid era and early Parthian period party in the period in question is an outstanding type which sounds unobtainable or minimally scarce in considerations. The pieces as such mostly attain light red and beige natural disposition, light rose-colored mantle painted like similar to the metal, fine mineral allegation, geometrical paintings, and animals in birds’ pictures being drawn ocher brown and black. The Potteries shape almost always indicates soft, ting bowls and cups the surface of which is well polished well-furnished and baked in a convenient temperature. The external similitude between late Seleucid and early Parthian potteries nourishes the persisting thought of such a tradition from Seleucid to Parthian. This research is to examining the recognition of the absence/presence of the production and business tradition of the Western Iran area in Seleucid/ early Parthian era. Therefore, using XRF and XRD methods, attempts have been made to deal with the identification of the compounds and elements used in grain utilized conforming western Iran painted pottery.
The propounded hypothesis in this regard is that they did discovered pottery type/species in the west area is possibly none native and imported. The native inference or pottery’s being imported deeply depends upon its natural disposition minerals compound similitude percentage with the minerals present in the area’s soil. In line whit this debate, three questions are replied:
1- How much similar to and different from one another are the soil elements used in Seleucid/ early Parthian painted potteries, compounds, being discovered excavated from some of the Iran Zones? 2- How homogeneous are the elements, present in texture and composition of Seleucid/ early Parthian painted potteries -being discovered in the west of Iran-, whit the structure elements and area geology zone? 3- Are these potteries similar to/different from one another in terms of composition, elements type, and baking conditions?
The selected samples of this research are prominent pieces which are picked up from three areas of Delfan, Alashtar, and Nahavand on ten of which laboratory experiments have been implemented. Among these prominent samples the option of each environment has been done. The XRF experiment on powdered samples has been done in Tarbiat Modarres university and XRD experiment has been implemented in Hamedan Bu-Ali Sina University physics lab, Tehran. These potteries are named as follows: Samples number 1(L.CH.T) from Chogha Taghi in Noor Abad City; sample number 2 (L.P.K) from Pat-koole; sample number 3 (L.Z.D) from Zarrin Deh Sefid tepe; sample number 4 (L.H.A.S) from Hassanabad Sanjabi; sample number 5 (L.CH.K) from Cheshme-Kaboud tepe; sample number 6 (L.A.A) from northern district of Noor Abad city; sample 7 (L.M.GH) from Adl-Abad village; sample number 8 (L.SH) from village Shaeile in Qalaei City; sample numbers 9 & 10 (H.N.L.1) & (H.N.L.2) from Loudich of Nahavand. 

Discussion
The results show that the silicon (oxide) rate is high in the samples obtaining low calcite (like sample number 9, and in the samples with high calcite, the silica (oxide) rate is low. Regarding the composition’s present in potteries body, making use of XRD and XRF methods, it can be inferred that the samples productions are associated with the area itself. Moreover, it can be stated that there are compounds such as Quartz in all soils, which is one of components of soil. There is calcite in all samples because of the presence of the calcareous sediments’ presence. The presence of the calcium carbonate and diopside in the potteries body indicates that the temperature of these potteries is less than 750 degrees centigrade. Three compounds of Aluminum oxide, Silica in Calcium carbonate (SiO2, Al2O3, Cao). Additionally, the percentage of the scarce elements in sample number 3 is different from the other ones. Except for these two, it seems that all of the samples are more or less similar to one another. The pottery’s body color is due to this element (Iron) and its oxidation, and red patterns upon potteries contain Iron as well. Pondering upon most of the painted potteries samples of early Parthian / Seleucid era from  Western Iran, it seems that their color is not that beige in comparison with the Clinker pottery type from Parthian era, which are mostly related to the middle and late of this era, and less homogeneity is observed in their color in comparison white Clinker pottery. These results assert that the production of Seleucid/ early Parthian period painted pottery in comparison with Parthian period Clinker pottery should be considered from a different or perspective. There is Manganese in some of the samples number (7 & 9 and little rate in sample 3) the black color of which possibly contain such an element. The presence of Calcium can be because of the calcareous sediments (probably) or some gypsum in the sample. The presence of sediment on all of the samples stems from burial area, moisture, and its omission then, and formation of calcareous sediments as well. The other elements such as Sodium, Potassium Phosphorus, and Titanium are among the ones present in the soil, the rate of which is from some percentage to a few hundred percent.

Conclusion 
The results of XRF & XRD analysis show that the major part of the examined potteries samples including three compounds of Aluminum oxide, Silica in Calcium carbonate (CaO, Al2O3, SiO2). This compound indicates that there is a share of the soils of the transformations stones (SiO2) in the soil used in building mentioned potteries in addition to calcareous soils (Al2O3, CaO). There is Manganese in some of samples (number7, 9, and a little rate in number 3 simple) which possibly has been because of the pigments usage for decorating the potteries patterns. Moreover, the existence of calcium can be possibly due to calcareous sediments or some plaster in the sample which implies the presence of sediment on all of the samples because of the burial area moisture, and then it’s elimination and calcareous sediments formation. The results demonstrate that the Seleucid/ early Parthian period painted potteries obtain more silica (oxide) rate in comparison with Parthian period Clinker pottery (the late and middle of this period), bring analyzed in western Iran, and also it attains a lower Calcite rate in comparison with Clinker potteries type. According to the potteries external features in terms of color and patterns, the similarity between- the ingredients of raw material (soil) is obvious in making pottery, indicating the production of the Portway in research area of although these painted  potteries of Seleucid often there is less homogeneity in their color in western Iran; and also, their baking technique and mode from pottery are similar with one another, and improve their native and domestic production (it is worth mentioning that there has no analysis regarding  Seleucid/ Parthian period painted pottery in the other areas been done) and it eliminates the issue of importing production of  Seleucid/  early Parthian period painted potteries. 

Abstract
This study aims to recognize and characterize pottery production at the Hormangan site, a Neolithic settlement in the northeast of Fars province, Iran. An examination and analytical study of the potteries on this site was conducted to determine the manufacturing techniques of the Neolithic potteries, understand the raw materials and inclusions, the level of progress and knowledge of the potters from the final products, and the location of the production site. Excavating this site, ceramics and a heated structure, probably an open kiln, were found, belonging to the Mushki phase (6400-6000 BC). Thirty-six ceramic shreds were selected for thin-section petrography analysis according to their macroscopic features. After that, 18 of them were analysed using X-Ray Fluorescence (XRF) and X-Ray Diffraction methods. According to the mineralogical studies and the XRD and XRF analyses, while three different clay types were used to produce these Neolithic ceramics, they were all local productions. These vessels were fired in an open and unsophisticated kiln at an uncontrolled temperature, probably not over 800 degrees. Although the combination of these archaeometrical techniques indicates that there are various sub-angular inclusions in each type of clay, most of the pots are vegetally tempered (chaff-tempered). The existence of the heated structure separately from residential construction, a variety of designs and decorations on the ceramics, and various clay sources all determine that the Neolithic community of the Hormangan site has gone beyond a primitive rural society and as semiprofessional individuals had a surplus of more than their demands.
Keywords: Neolithic Period, Hormangan Site, Ceramic Production, Petrography, XRD, XRF.

Introduction
Hormangan site is a Neolithic site located on the border of the Bavanat River basin, in Jeshnian village, in the northeast of Fars province, Iran. This site was excavated in 2016, revealing two phases dated back to 6373 to 6000 BCE. The earlier phase indicates no traces of architectural structures, and the later phase contributed to the settlements. Moreover, a heated structure was discovered simultaneously with the later phase, surrounded by potteries and divided spaces. Pottery vessels which were discovered from these two phases are similar to the ceramics of Tall-e Mushki, Tall-e Jari B, Kushk-e-Hazar, Tall-e Bashi, and Rahmat Abad. As these types of potteries were first discovered from the Tall-e Mushki, they are known as Mushki phase potteries. The heated structure discovered in the Hormangan site is a unique structure related to producing pottery during the Mushki phase, which was probably an open fire kiln. Since there are no similar structures have been found in the Neolithic sites in the Fars region, this study aims to understand pottery manufacturing technology with multi-analytical approaches. Moreover, considering the two phases of the Hormangan site occupied by different settlers for almost 300 years, it is attempted to differentiate potteries of these two phases from a technological point of view.

Geological Setting
A portion of the Bavanat plain lies in the Sanandaj-Sirejan zone, as well as the Shahreza-Abade- Hambast orogenic belt, characterised by high-quality clay deposits and Devonian sandstones (Houshmandzadeh and Soheili, 1990). Several types of rocks can be found in the Bavanat region (Emami and Yaghmai, 2008), spanning three tectonic-stratigraphic units: Late Permian and Middle Triassic rocks, Late Triassic and Cretaceous rocks, and Tertiary rocks (Ghazi and Moazzen, 2015; Ghorbani, 2011). From the mineralogical point of view, this area includes kaolinite, illite, quartz, and chlorite, and secondary minerals are goethite, paragonite, and gypsum. Also, sandstones and shales have been eroded in most cases, creating debris slides. There is a large hydrographic network density in Tutat Mountain (formed by internal and metamorphic formation). However, there is a lower density of hydrographic network in the Kitaban, Khaleisht, and Khatban Mountains. The clays in this region are therefore expected to contain high levels of lime and quartz minerals, but it is also likely to contain metamorphic minerals (Khademi and Hashemi Nasab, 2011).

Materials and Methods
Hormangan ceramics were primarily divided into six groups based on surface treatment, colour, and decoration style. In further classification, the Hormangan potteries were categorised based on their form, size, place of motifs and ceramic fashioning techniques. After initial macroscopic studies of these ceramic vessels, 36 pottery sherds were selected for thin-section petrographic analysis. For choosing these samples, not only the former classifications were considered, but also it was attempted to select potteries from different phases and various contexts and trenches. The earlier phase includes 14 samples, the later phase 12 samples, and the heated structure 10 samples were selected for this analysis. 
For getting inside into the primary and secondary mineralisation phases, determining firing conditions and maximum temperature, and environmental burial conditions, 18 samples (from those 36 samples) have been selected for the X-Ray Diffraction analysis (XRD) in order to determine the crystalline phase constituents. This methods is necessary as a complementary method to petrography. Moreover, X-Ray Fluorescence analysis as a semi-quantitative analysis has been applied to these 18 samples to detect the chemical characterisation of their main and trace elements and to identify whether the earlier and later phases’ samples become clustered into two different groups or not. 

Discussion
The thin-section microscopic analysis indicated a very porous matrix with angular and semi-angular inclusions, which are mainly quartz, and with traces of vegetal tempers. Moreover, the vessels were fired under the oxidation condition. The inclusions were distributed randomly in the matrix, which suggested that they were not homogeneous and consisted of quartz, limestone, calcite, plagioclase (albite and sanidine), and igneous rock fragments, including muscovite, iron oxide, granite, magnetite, hematite, apatite, and feldspars. In most sherds, secondary calcite was formed, resulting in burial in a humid condition. The XRD analysis enabled us to observe some high-temperature minerals, such as gehlenite and diopside, in some samples. These minerals are usually presented in ceramics when fired at more than 800 degrees. On the other hand, the presence of the main elements MgO+CaO, Al2O3, and SiO2, detected by the XRF analysis and diagramed by the Noll system, indicated a very similar final product in terms of raw materials and inclusions. In addition, Cl, MnO, and SrO have been identified in these samples as trace elements, indicating the environmental conditions of the vessels after abandonment. 

Conclusion
In light of the microscopical observations and the phase and chemical analyses, it was determined that the Hormangan potteries could be divided into three main groups. The potteries of the earlier and later phases could not be distinguished from one another. These three groups are comparable to the region’s geological map, meaning all potteries are locally made. Except for four samples that were fired above 800 degrees, the others were fired at temperatures around 750 degrees. Samples from the earlier and later phases were distributed randomly among these clusters, comprising the Calcareous, Iron-rich, and Calcium-rich matrixes. The clay minerals were all extracted in the vicinity of the site, despite the fact that there were three different types of clay materials. Therefore, the potter(s) at the Hormangan site have chosen diverse clay sources but employed different techniques each time to produce similar results. It has also been noted that samples obtained from the heated structure have very similar characteristics to the ceramics produced in the later phase. According to the absolute dating results, the heated structure and the later phase are contemporaneous. However, in terms of potters’ technological behaviours, this could point to some standardization of ceramic production during this time.
Another question we have attempted to answer is whether the potter(s) added any aplastic materials, such as quartz, to their clay in order to increase its workability. Based upon an ethnoarchaeological study of the current pottery production in ShahReza (Pincé et al., 2019), approximately 230 kilometers away from the Hormangan site, it has been found that additional tempering does not need to be applied to the clay for the production of ceramics, owing to the rich clay sources in the ShahReza-Abade-Hambast orogenic belt (located in the Sanandaj-Sirjan zone). There is a possibility that the richness of clay sources in this region allowed potters to avoid tempering their raw materials during different periods, which will be investigated in more detail in future studies.   

Acknowledgements
Dr Morteza Khanipour has generously allowed access to the Hormangan site’s ceramics for this study, and the authors are very grateful for his generosity.

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.