Abstract
One of the most critical found objects from the site of Shahr-i Sokhta are lapis lazuli stones and beads, which were used as stone jewelry and ornaments. One of the site’s most significant archaeological and archaeometry topics is the way of manufacturing and types of stone structures into these objects. The Shahr-i Sokhta’s lapis lazuli beads manufactured with flint borers are in the forms of lens, lozenge, circle, etc., and were used as jewelry and ornaments such as bracelets, anklets, necklaces, etc. The main discussion in this research is recognizing the structure and studying the mineralogy of lapis lazuli beads discovered from Shahr-i Sokhta. Hence, by using laboratory-device methods such as petrography of thin sections, X-ray energy diffraction microanalysis, Raman Spectroscopy analysis, and gemology methods, this research studies the structures of three samples of lapis lazuli beads and stones of Shahr-i Sokhta. The results of laboratory studies show that Shahr-i Sokhta’s structure of lapis lazuli stone consists of lazurite minerals with a high percentage of calcite mineral impurities, which causes a reduction of transparency and purity of the lapis lazuli stones; also, elemental studies represent the presence of lazurite minerals. Raman structural and gemological studies show the structure, the amount of absorption coefficient, and its specific weight in the main structure of lapis lazuli stone. Chemical and structural studies indicate that the stones are similar in terms of composition.
Keywords: Stone Jewelries, Lapis Lazuli, Archeaometry,  Shahr-i Sokhta in Sistan, South-east of the Iranian Plateau.

Introduction
Shahr-i Sokhta is one of the most important and key sites among Bronz-age sites in southeast Iran’s archaeology (Biscione et al., 1974; Tosi, 1968, 1969, 1973; 1976; Tosi and Piperno, 1975; Savatori & Vidale, 1997; Piperno & Salvatori, 2007). Through excavations during different years up to now, a vast majority of semiprecious Stones and jewelry have been discovered; some of them are healthy beads in the form of necklaces, bracelets, and anklets, while others are half-worked beads as well as raw stone and blocks (Foglini, 1998). The jewelry is lapis lazuli, agate, chlorite, turquoise, limestone, flint, jasper, marble (calcite and aragonite), quartz, green tuff, and chert; that one of the most significant of them is lapis lazuli which was brought to Shahr-i Sokhta as a result of the trade from other regions. lapis lazuli stone in various forms and shapes is the most discovered abundant cultural material in Shahr-i Sokhta (Sajjadi, 2005, 2007). The discovered lapis lazuli are healthy and semi-worked, as well as raw and discarded material. The archaeological studies have demonstrated that the raw lapis lazuli blocks were imported into Shahr-i Sokhta, and then they were changed into various artifacts by artisans (Farzin et al., 2019). Hence, recognizing the structure and method of manufacturing the discovered lapis lazuli beads from Shahr-i Sokhta could be one of the most important topics for archaeologists. The archaeo-gemological study is a field of archaeometry that investigates and recognizes the structure and method of manufacturing and polishing these semiprecious Stone ornaments and jewelry. Archaeo-gemological studies examine minerals, gem materials, and jewelry, which were used as ornaments, decorative objects, jewelry materials, etc., in particular eras and places of the ancient world (Hatipoglu & Guney, 2013; Rapp, 2009; Dominguez-Bella, 2012). Therefore, this research based on Archaeo-gemological studies investigates the preliminary lapis lazuli stone jewelry produced in Shahr-i Sokhta.

Material and Methods (Samples)
The selected samples in this research include three pieces of lapis lazuli discovered from the archaeological survey of Shahr-i Sokhta. One of the samples is a raw material with a small incision that had been discarded as waste (SH-L1). The other one is a rectangular object with grooves in its width, which was broken during use (SH-L2), and the last one is a tiny bead; all three are studied in this research (SH-L3).

Methods
Microscopic thin section petrography (OPM) is administered to examine the samples under a polarizing microscope. The device model used in this research is James Swift, made in England.
The elemental Micro-analysis EDX method is applied to recognize samples chemical combinations. This examination is conducted through EDX devise coupled with a field emission electron microscope (FESEM) manufactured by Tasken company, model MIRA3TESCAN-XMU.
For structural investigation of the samples, this research uses Raman spectroscopy examination through (Takram) P50C0R10 model device, Taskan company in Raman laboratory. This device has a laser wavelength of 532nm (Nd: YAG Laser), and the range of Raman shift RS is 100-4600.
Moreover, this study uses gemological methods such as specific weight and refractive index to identify the samples.

Results
Petrography
According to the petrographic studies of the lapis lazuli samples under a polarizing microscope, blue lazurite minerals are seen with white calcite.
 
Raman Spectroscopy
The obtained spectra from this chart are compared with the reference spectrum at http://www.rruff.info This comparison indicates the existing lazurite in the stone structure of Na3Ca(Si3Al3)O12S. There is a Raman spectrum in the range of 546 cm-1, 1092 cm-1, and 254 cm-1, and the intensified spectrum is high in the range of 546 cm-1, considered the main spectrum.

EDX
Micro-analysis (EDX) Obtained spectra in the formula of these stones represent the amount of silicon (19/61 and 19/11), aluminum (7/14 and 7/21), magnesium (7/98 and 6/73), calcium (4/98 and 4/94), and sodium (3/46 and 3/13) elements with the highest abundance.

Gemological Analysis
This part investigates these lapis lazuli’s mineralogical features through two refractometer methods and the determination of specific weight. 

Refractometer
Among Shahr-i Sokhta’s studied samples, this research has selected three lapis lazuli samples to study. For investigating, first, one drop of special liquid (REFRACTOMETER LIQUID-Nd 1.81) is poured into the location of the samples; second, the flat sides of the gems locates on the oil. Then, by turning on the device lamp and closing the deflectometer cap, one could obtain each sample’s refractive coefficient measure by reading the refractive coefficient. The type of the studied sample has been identified by measuring the refractive coefficient of the samples and comparing obtained numbers with the standard table of gems (GIA- GEM PROPERTY CHART). The refractive coefficient of 1.50 is related to lapis lazuli stone.

Determination of Specific Weight
One of the quick identifying ways of the gems is the determination of their specific weight, which causes no damage to the gems. To obtain the particular weight of each mineral or gem, first, they are weighted in the air and then in the water. Next, by using a formula, the amount of specific weight is calculated. The particular weight of the discovered lapis lazuli samples of Shahr-i Sokhta is 2.1-3.3. 

Conclusion
Microscopic investigations based on the thin section petrography show that the structure of studied lapis lazuli is lazurite mineral type with calcite minerals. In microscopic images, Lazurite minerals clearly are blue, calcite minerals in the stone texture are white, and pyrite minerals rarely can be seen in the studied stone texture. Identifying the existence of a significant amount of calcite and a poor amount of pyrite in the lapis lazuli structure represents the amount of impurities in these stones. Furthermore, elemental analysis of the three lapis lazuli indicates that there are other elements with the highest frequency; these elements are silicon (20/95 and 20/67), aluminum (7/80 and 7/63), magnesium (7/28 and 8/52), calcium (4/94 and 5/33), sodium (3/34 and 3/74) and sulfur (0/66 and 1/09). In fact, lapis lazurite is a blue stone whose chemical composition is variable, and its basic composition is mineral lazurite consisting of aluminum, calcium, and sodium silicates. Lapis lazuli consists of several different minerals, such as sodalite, hauynolith, calcite, pyrite, and lazurite, which are lapis lazuli’s main components. Fewer white calcite spots and more yellow pyrite in the lapis lazuli indicate the best quality of the lapis lazuli. In table 3, silicon element (29.87%) and calcium element (12.26%) are the most amounts of compounds in the Shahr-i Sokhta lapis lazuli structures. The identified chemical compositions of the lapis lazuli in Shahr-i Sokhta are a high amount of calcium and a low amount of iron, which indicates the lapis lazuli structure of this site has a high calcium impurity and low pyrite impurity; this issue could be confirmed through petrography studies. Finally, this analysis represents the correct recognition of the composition and type of used stones in manufacturing ornament objects of Shahr-i Sokhta.
The element percentage of obtained spectra is clearly determined, indicating the main composition of lapis lazuli. The elements represent the chemical structure of a lapis lazuli, a lazulite mineral type with a high calcite impurity percentage. In addition, this study examines the three pieces of lapis lazuli samples through Raman spectroscopy; two samples represent almost similar peaks in the range of 546 cm-1 and 1092 cm-1, and only one sample shows a peak in the range of 546 cm-1. The investigations represent that based on the lapis lazuli studies using the Raman, the lapis lazuli in the mentioned ranges shows an almost significant peak. The number of elements and obtained spectra in these two spectra are almost similar.

Acknowledgments
This work has been supported by the “Investigation and study of Shahr-i Sokhta semi-precious stones” project funded by the Research Center for Conservation of Cultural Relics (RCCCR). The authors are thankful to Center for Conservation of Cultural Relics. The authors want to National Museum of Iran, Southeast Regional Museum of Zahedan, and Shahr-i Sokhta World Heritage Site for their supporting.

Abstract
Due to the construction of the Seymareh Dam and the risk of flooding the archaeological site ‎known as “Pir Mikail,” conducting salvage excavations at this site became an unavoidable ‎necessity. At the highest point of the mound, a stone structure with an irregular plan was ‎situated, initially hypothesized to be a Sasanian Chahartaq (four-arched structure). Accordingly, ‎the excavation was carried out with the aim of identifying the nature of the structure, ‎understanding the settlement pattern at the site, and examining the surrounding remains and their ‎interactions with one another. The present research is based on a descriptive-analytical method ‎with a field and comparative approach, as well as historical sources, and seeks to answer the ‎following questions: What is the nature of the stone structure located at the summit of the ‎mound? Is it a Sasanian Chahartaq or an Islamic-era tomb? What other remains does this site ‎contain, and what interactions and functions have these remains had with each other or with ‎other neighboring sites? What factors have influenced the formation of human settlements and ‎architecture in this region? The excavation results revealed that the main structure was not a ‎Sasanian Chahartaq but rather a tomb belonging to the middle Islamic period. In the southern part ‎of the site, the remains of a coherent architectural complex belonging to the Sasanian period were ‎identified, including spaces with barrel vaults and lime plaster coating, as well as a columned ‎hall. Furthermore, evidence indicates that this site was connected to the “Shahr-e Viran” complex ‎and a communication route. Overall, the findings suggest a continuity of settlement sequence at ‎the Pir Mikail site from the Sasanian period to the early Islamic centuries, and continued activity ‎in its central part until the late Middle Islamic centuries.‎
Keywords: Archaeology, Simareh, Sasanian, Pir-Meka’il Site, Kuhdasht.

Introduction
The Seymareh Valley has persistently attracted human societies due to its natural characteristics, strategic position, and fertile water and soil resources. This valley constituted one of the major civilizational hubs during the Sasanian and Islamic periods. Historical texts refer to it as part of the province of “Pahleh,” which comprised two principal districts: “Māsabadhān” in the north (modern-day Ilam Province), centered on the Sasanian city of Sirwan, and “Mihrajān Qadhaq” (also recorded as Qadhaq) in the south, centered on the city of Seymareh (Balādhurī, 1376/1997: 433). According to historical sources, these cities retained their significance until the early Islamic centuries. Despite the identification of numerous ancient city remains along the valley, some—such as “Shahr-e Rudbār”—have not yet been subjected to archaeological study and excavation.
The construction of the Seymareh Dam and the consequent risk of inundation rendered salvage archaeological excavations an unavoidable necessity at sites within the reservoir catchment area, including “Pir Mikā’il.” Archaeological data pertaining to the Sasanian period across present-day Iran have largely been obtained from other provinces. Recent discoveries of architectural evidence and remains in the Seymareh Valley, however, can provide a new model for settlements of this period in the Central Zagros and Lorestan regions. The studied site is located approximately at the far end of the Seymareh Valley in Lorestan Province. At the highest point of this low elevation mound, a stone structure was present, initially hypothesized to be the remains of a Sasanian Chahartaq (four arch structure). The distribution of surface sherds further confirmed the existence of occupation during the Sasanian and Islamic periods.
Excavation at this site was undertaken as a salvage necessity, with the objectives of identifying the site’s remains, determining the nature, function, and date of the stone structure, elucidating the interrelationships among the architectural features, and understanding the role and significance of these structures within the cultural and geographical context of the region. This research, predicated on the hypothesis that the aforementioned site contains previously unknown remains from the Sasanian and Islamic periods, commenced with the following research questions: What is the nature of the stone structure located atop the mound? Is this structure a Sasanian Chahartaq or an Islamic period tomb? What other remains does this site contain? What interactions and functions did these features have with one another or with other features at neighboring sites? What factors have influenced the formation of human settlements and architecture in this region?

Discussion
The most significant excavation data include:
A. Islamic Period Structure: Excavations in the central part of the site revealed a mausoleum measuring approximately 8x8 meters. The building materials consist of local natural limestone, such as large and small dressed cubic stones, sometimes irregular, along with rubble stone and cobbles, bonded with a semi-crushed, reddish-tinted gypsum mortar.
b. Sassanid Period Architectural Findings: Remains of a regular architectural complex, consisting of several interconnected spaces built with natural stone and gypsum mortar, were identified. To increase the strength of the walls, the stones were laid with gaps between them, and the empty spaces were filled with a significant volume of mortar to enhance the structure’s adhesion and resistance. Overall, the main structure includes a quadrangular space and columned halls.
c. Quadrangular Space: This refers to a quadrangular room with approximate dimensions of 360×270 cm. The discovery of arched gypsum fragments within the ceiling debris indicates that this space was covered with a barrel vault.
d. Columned Halls: Adjacent to the quadrangular space, two columned halls were also identified, each featuring a central quadrangular pier of stone and gypsum mortar acting as the middle column. Comparing this structure with similar examples suggests that the roofs of these halls were also vaulted. The internal and external surfaces of the walls were covered with a layer of gypsum plaster, 3 to 5 cm thick.
e. Enclosure Wall: In the northwestern sector of the Sassanid site, a dry-stone wall (without mortar) built with stones averaging 10×15×17 cm in size was discovered. Only one course of stones remains from this wall, which has a width of 80 cm and a remaining height of between 40 and 45 cm.
f. Remains of an Ancient Road: At the far end of the site, in its southwestern sector, parallel to the discovered enclosure wall and above the Qanat’s outlet, traces of an ancient road running northwest to southeast were identified. This road, with a width between 3 and 4 meters, ran parallel to the river and established a connection between Sirvan and Seymareh.
g. Qanat: This Qanat was identified in the southern area of the site. It transported potable water from the mountain aquifer foothills to the structures located along the banks of the Seymareh River and to the Qanat’s outlet (mazhar).
The aqueduct’s structure consists of vertical wells with an average depth of 7 meters and a gentle slope. This aqueduct channel consists of two main parts: the “arch” (with a semicircular arch and, in some parts, a “keyhole arch” type) and the “body”.

Conclusion 
Archaeological excavations revealed that the main structure in the central part of the site, contrary to the initial hypothesis, was not a Sasanian Chahartaq but rather a solitary mausoleum belonging to the Islamic period.
However, the archaeological findings in the southern part of the site include the remains of a coherent complex of spaces featuring barrel vaults, semicircular arches, and columned halls (with stone piers and semi-crushed gypsum mortar), constructed using stone and gypsum. The presence of a columned hall alongside spaces with barrel vaults constitutes a distinctive characteristic of this complex, indicating a combination of two architectural styles, both belonging to the Sasanian period. Other notable architectural features include the use of small arched openings as doorways, delicate gypsum-plastered niches on the interior walls, and the employment of simple gypsum blocks in door frames.
Considering the structural similarities with Sasanian sites within the catchment area of the Seymareh Dam—such as the materials used, arched doorways, symmetrical niches, as well as the presence of pottery sherds of the same style at the site, which correspond to typical Sasanian-period examples—a Sasanian date is proposed for this structure.
The contemporaneous functioning of the Qanat with other surrounding features provides strong evidence for the existence of an organized settlement dependent on this water system during the historical Islamic period. This Qanat not only represents a rare example of indigenous water engineering but also clearly illustrates the connection between nature, technology, and human settlements, manifesting the intelligent interaction and adaptability of human habitations with the natural environment within a historical framework.
Although a definitive statement regarding the precise function of the Sasanian structure remains difficult, its location downstream of the “Shahr-e Virān” (the ruined city) site, the presence of traces of an ancient road to its west, its proximity to the rock-cut Qanat, as well as its general architectural features and ceramic evidence, all indicate the interaction of this complex with its surrounding environment. It seems that this complex served to secure the communication route between Sirwan and Seymareh during the Sasanian and early Islamic periods. The presence of collapsed arched vaults and destroyed walls made of stone and saruj (a traditional lime-mortar) likely points to a devastating earthquake (in the 3rd century AH / 9th century CE), which caused serious damage to the Qanat and the building complex, leading to their abandonment and eventual complete destruction of the site, as well as the destruction of “Shahr-e Virān.” In sum, the architectural evidence and ceramic data confirm the settlement sequence of the site from the Sasanian period, with continued occupation into the early Islamic centuries.