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Ali Aarab, Mohammad Bonyadi Nezhad, Seyedeh Iraj Beheshti, Vahid Azadi,
year 3, Issue 7 (5-2019)
year 3, Issue 7 (5-2019)
Abstract
Abstract
The previous studies on the Elamite pottery generally focused on the form and shape of the artifacts. From the perspective of fabric, very few studies have explored the Elamite pottery. The pottery type studied in this paper is orange (ranging from light brown to red) composed of a tempering material, sand and white particles. The core of this no ornamented, wheel-built pottery is black. In an investigation to outline the scope and boundaries of Haft Tapeh ancient city, a number of the Elamite pottery samples were recovered in certain layers dating back to the late ancient Elam (Sukalmah) and the Middle Elamite near the adobe structures of Haft Tapeh. Haft Tapeh refers to a structure belonging to the Elamite Era located in Khuzestan and south of Susa. One major finding in this city is a tomb from the Middle Elamite Era. Since 1965, this building has been investigated by Negahban and later by Mofidi-Nasr abadi. Thus, Haft Tapeh can undoubtedly be considered a city belonging to the Elamite Era. In this light, the pottery type in this geographical scope can be particularly useful for comparison of similar artifacts found in Isfahan and Chaharmahal and Bakhtiari, both of which could be associated with the Elamite Era. This study focused on Asgaran and Saba as two regions in Isfahan and central part of Ardal in Chaharmahal and Bakhtiari. A total of 10 pottery samples were randomly selected from these regions. They were then compared in terms of fabric and composition against 4 counterparts found in archaeological layers of Haft Tapeh belonging to the Elamite Era. It should be noted that the two-color body in the pottery sample is not at all associated with the type of compounds or curing temperature, Since the two parts are identical in terms of composition. Moreover, it seems that the main reason for the two-color body lies in the curing conditions and techniques (oxidation and reduction) inside the furnace, leading to two different colors. Apart from that, there is a kind of orientation in the components of pottery samples, potentially indicating they were built on wheels.
Keywords: Elam, Orange-Red Pottery, Petrography, XRD, Ft-IR.
Introduction
One of the surrounding regions cover the north of present-day provinces Fars and Khuzestan as Elamite centres in the ancient era. The noteworthy point about these regions is their potentially rich metal mines. This has been mentioned in the Mesopotamian inscriptions, mainly explaining the link between the Mesopotamian plain and the highlands of Elam. The present-day provinces, Khuzestan and Fars, have small potentials for metal mines. Hence, they only served as surrounding regions supplying the metals. However, little investigation has been done on the archaeological data from the Elamite Era. It is crucial to carry out a historical study on these regions along with the archaeological data to enlighten the dark spots in the Elamite Era, and ultimately provide a toponymy of the Elamite cities. One instance of such archaeological data involves various types of local pottery in Khuzestan (as a central city of Elam), which was compared through petrography against the samples recovered in Isfahan and Chaharmahal and Bakhtiari (as two dently the era in surrounding regions). Thus, this paper intends to discuss more con which this type of pottery was built and its origin in order to provide a toponymy of the previously mentioned cities based on historical and archaeological data. In Miankooh, Ardal, more than 76% of Elamite sites have been reported to be nomadic. This is highly important alongside the neighborhood of this province and Isfahan with regard to the toponymy of Zabshali and LU.SU. Meanwhile, there are a considerable number of pottery samples from this region comparable to their counterparts across the Elamite centers.
The surrounding regions of Elamite centers (Susa and Anshan) have so far been rarely explored. One of such surrounding regions stretched across the norther of Elamite centers, covering certain areas of present-day provinces Isfahan and Chaharmahal and Bakhtiari. In addition, there are pottery samples from the Elamite Era found in Khuzestan (as one of the central districts of Elamite), even though they have rarely been explored in studies on the Elamite Era. This can be partly associated with the limited number of such pottery samples against their counterparts from the Elamite Era in Khuzestan. Nonetheless, the noteworthy point about this pottery type is the great similarity (discussed later) in Khuzestan to those recovered in Isfahan and Chaharmahal and Bakhtiari. Therefore, this study attempted to explore these regions from the Elamite Era through an interdisciplinary approach involving archeology, archeometry and history of northern Susa and Anshan. Despite the importance of the regions surrounding Elamite centers (Susa and Anshan) based on the Mesopotamian inscriptions, insufficient effort has so far been made to investigate the Elamite Era in Isfahan and Chaharmahal and Bakhtiari as two surrounding regions. Nevertheless, the pottery type studied in this paper has been frequently found in Isfahan and Chaharmahal and Bakhtiari. In this study, great effort was made to review the geographical locations of the two provinces in Elamite Era according to written sources and archaeological evidence. Moreover, the pottery artifacts were petrographically examined to find out whether or not the samples recovered in Haft Tapeh, as a key central spot in Khuzestan during the Elamite Era, are congruent with the clay artifacts found in Isfahan and Chaharmahal and Bakhtiari from the perspective of appearance and textural characteristics. In fact, the discussion revolves around the possible involvement and predominance of the Elamite in Isfahan and Chaharmahal and Bakhtiari, while providing a toponymy of ancient Elamite regions in those provinces today.
Conclusion
The specific pottery type in this study indicated a remarkable frequency in Isfahan and Chaharmahal and Bakhtiari. Moreover, it proved to be similar to counterparts recovered at Haft Tapeh (Khuzestan) in terms of fabric, production technique and curing temperature. It is essential to point out the pottery types across the northern Elamite centers which have been rarely explored so far. The specific pottery type examined in this paper can definitely be considered an Elamite artifact. It should originate from the Zagros Mountains in the north of Khuzestan (Bakhtiari highlands). That is perhaps why this type of pottery is less abundant in Khuzestan as opposed to Isfahan and Chaharmahal and Bakhtiari. According to the constituent element of pottery samples, this pottery type does not originate from Khuzestan Plain, but it can rather be traced in Zagros Mountains. Therefore, it can be argued that the Elamite were involved in dominated Isfahan and Chaharmahal and Bakhtiari, while delving into the toponymy of Elamite cities such as Zabshali and Tukrish in certain parts of Isfahan and LU.SU in Chaharmahal and Bakhtiari. The regions never explored from that very perspective can set out a new avenue of Elamite research into these Iranian provinces. Finally, it is recommended that future studies focus on northern regions of Elamite centers including the present-day Isfahan, Yazd and Chaharmahal and Bakhtiariti so as to clarify many of the archaeological ambiguities of Elamite Era. After all, an in-depth investigation of Mesopotamian inscriptions can help scholars realize the importance of these regions, while revealing their archaeological capacities.
The previous studies on the Elamite pottery generally focused on the form and shape of the artifacts. From the perspective of fabric, very few studies have explored the Elamite pottery. The pottery type studied in this paper is orange (ranging from light brown to red) composed of a tempering material, sand and white particles. The core of this no ornamented, wheel-built pottery is black. In an investigation to outline the scope and boundaries of Haft Tapeh ancient city, a number of the Elamite pottery samples were recovered in certain layers dating back to the late ancient Elam (Sukalmah) and the Middle Elamite near the adobe structures of Haft Tapeh. Haft Tapeh refers to a structure belonging to the Elamite Era located in Khuzestan and south of Susa. One major finding in this city is a tomb from the Middle Elamite Era. Since 1965, this building has been investigated by Negahban and later by Mofidi-Nasr abadi. Thus, Haft Tapeh can undoubtedly be considered a city belonging to the Elamite Era. In this light, the pottery type in this geographical scope can be particularly useful for comparison of similar artifacts found in Isfahan and Chaharmahal and Bakhtiari, both of which could be associated with the Elamite Era. This study focused on Asgaran and Saba as two regions in Isfahan and central part of Ardal in Chaharmahal and Bakhtiari. A total of 10 pottery samples were randomly selected from these regions. They were then compared in terms of fabric and composition against 4 counterparts found in archaeological layers of Haft Tapeh belonging to the Elamite Era. It should be noted that the two-color body in the pottery sample is not at all associated with the type of compounds or curing temperature, Since the two parts are identical in terms of composition. Moreover, it seems that the main reason for the two-color body lies in the curing conditions and techniques (oxidation and reduction) inside the furnace, leading to two different colors. Apart from that, there is a kind of orientation in the components of pottery samples, potentially indicating they were built on wheels.
Keywords: Elam, Orange-Red Pottery, Petrography, XRD, Ft-IR.
Introduction
One of the surrounding regions cover the north of present-day provinces Fars and Khuzestan as Elamite centres in the ancient era. The noteworthy point about these regions is their potentially rich metal mines. This has been mentioned in the Mesopotamian inscriptions, mainly explaining the link between the Mesopotamian plain and the highlands of Elam. The present-day provinces, Khuzestan and Fars, have small potentials for metal mines. Hence, they only served as surrounding regions supplying the metals. However, little investigation has been done on the archaeological data from the Elamite Era. It is crucial to carry out a historical study on these regions along with the archaeological data to enlighten the dark spots in the Elamite Era, and ultimately provide a toponymy of the Elamite cities. One instance of such archaeological data involves various types of local pottery in Khuzestan (as a central city of Elam), which was compared through petrography against the samples recovered in Isfahan and Chaharmahal and Bakhtiari (as two dently the era in surrounding regions). Thus, this paper intends to discuss more con which this type of pottery was built and its origin in order to provide a toponymy of the previously mentioned cities based on historical and archaeological data. In Miankooh, Ardal, more than 76% of Elamite sites have been reported to be nomadic. This is highly important alongside the neighborhood of this province and Isfahan with regard to the toponymy of Zabshali and LU.SU. Meanwhile, there are a considerable number of pottery samples from this region comparable to their counterparts across the Elamite centers.
The surrounding regions of Elamite centers (Susa and Anshan) have so far been rarely explored. One of such surrounding regions stretched across the norther of Elamite centers, covering certain areas of present-day provinces Isfahan and Chaharmahal and Bakhtiari. In addition, there are pottery samples from the Elamite Era found in Khuzestan (as one of the central districts of Elamite), even though they have rarely been explored in studies on the Elamite Era. This can be partly associated with the limited number of such pottery samples against their counterparts from the Elamite Era in Khuzestan. Nonetheless, the noteworthy point about this pottery type is the great similarity (discussed later) in Khuzestan to those recovered in Isfahan and Chaharmahal and Bakhtiari. Therefore, this study attempted to explore these regions from the Elamite Era through an interdisciplinary approach involving archeology, archeometry and history of northern Susa and Anshan. Despite the importance of the regions surrounding Elamite centers (Susa and Anshan) based on the Mesopotamian inscriptions, insufficient effort has so far been made to investigate the Elamite Era in Isfahan and Chaharmahal and Bakhtiari as two surrounding regions. Nevertheless, the pottery type studied in this paper has been frequently found in Isfahan and Chaharmahal and Bakhtiari. In this study, great effort was made to review the geographical locations of the two provinces in Elamite Era according to written sources and archaeological evidence. Moreover, the pottery artifacts were petrographically examined to find out whether or not the samples recovered in Haft Tapeh, as a key central spot in Khuzestan during the Elamite Era, are congruent with the clay artifacts found in Isfahan and Chaharmahal and Bakhtiari from the perspective of appearance and textural characteristics. In fact, the discussion revolves around the possible involvement and predominance of the Elamite in Isfahan and Chaharmahal and Bakhtiari, while providing a toponymy of ancient Elamite regions in those provinces today.
Conclusion
The specific pottery type in this study indicated a remarkable frequency in Isfahan and Chaharmahal and Bakhtiari. Moreover, it proved to be similar to counterparts recovered at Haft Tapeh (Khuzestan) in terms of fabric, production technique and curing temperature. It is essential to point out the pottery types across the northern Elamite centers which have been rarely explored so far. The specific pottery type examined in this paper can definitely be considered an Elamite artifact. It should originate from the Zagros Mountains in the north of Khuzestan (Bakhtiari highlands). That is perhaps why this type of pottery is less abundant in Khuzestan as opposed to Isfahan and Chaharmahal and Bakhtiari. According to the constituent element of pottery samples, this pottery type does not originate from Khuzestan Plain, but it can rather be traced in Zagros Mountains. Therefore, it can be argued that the Elamite were involved in dominated Isfahan and Chaharmahal and Bakhtiari, while delving into the toponymy of Elamite cities such as Zabshali and Tukrish in certain parts of Isfahan and LU.SU in Chaharmahal and Bakhtiari. The regions never explored from that very perspective can set out a new avenue of Elamite research into these Iranian provinces. Finally, it is recommended that future studies focus on northern regions of Elamite centers including the present-day Isfahan, Yazd and Chaharmahal and Bakhtiariti so as to clarify many of the archaeological ambiguities of Elamite Era. After all, an in-depth investigation of Mesopotamian inscriptions can help scholars realize the importance of these regions, while revealing their archaeological capacities.
Parasto Masjedi-Khak, Mostafa Khazaei, Ali Aarab, Seyed Iraj Beheshti,
year 5, Issue 15 (6-2021)
year 5, Issue 15 (6-2021)
Abstract
Abstract
Due to the long lasting durability of pottery, they remain unchanged and plays an important role in archaeological researches. Aside of its difference usage in archaeological research such as dating, artistic and subsistent and communications and exchanges among people of different regions, is used in technology level. Archaeological site of Tape Kelar Hill, situated near Hasankif city, in Kelardasht, is one of the most important prehistoric sites in southern coast of Caspian Sea, which includes cultural materials from the Late Chalcolithic from the fourth millennium B.C. to the Islamic era. The significance of this site has become twofold considering the previous views issued about prehistoric cultures in western Mazandaran and Gilan provinces. The Early Bronze Age potteries of this site are of Kura-Araxes. These are the most important finds of this site. The main research question of this article pertains to the structure of the pottery in this area in two periods and aims to see whether or not the initiation of Kura-Araxes pottery has resulted from external factors and there is difference between Early and Middle Bronze Ages? In this study, 15 pieces of pottery from Early and Middle Bronze ages were studied via petrography method in order to compare in terms of composition and mineral tissues. Research has shown that the pottery of this site, in spite of experiencing some changes in the tissues, is local production. Therefore, it is rebutted to claim that the pottery of this culture is simulated by indigenous potters.
Keywords: Kura-Araxes, Middle Bronze Ages,Tape Kelar, Petrography.
Introduction
Petrographic study of Kura-Araxes pottery, despite its prevalence outside of Iran, has not received much attention from Iranian archaeologists. The first petrographic study of Kura-Araxes pottery in Iran was also conducted by Western archaeologists. The study of Kura-Araxes pottery in areas far from emergence region of this culture in Iran requires data from sites that had a stratigraphic-chronology continuity that was not available until the excavation of Tapeh Kelar.
In terms of the location of the sites studied by the petrographic method prior to the present study, two general classifications can be proposed: first, the sites that were within the geographical area of the origin of the Kura-Araxes culture, and second, the area- Those who are far away and outside the region of origin and only in the second stage of the development of the Kura-Araxes culture reached this culture.
This classification can be useful in analyzing the existence of trans-regional connections with the Caucasus or northwestern Iran, along with comparing the minerals of Tapeh Kelar pottery with the petrology of Kelardasht region. In this research, the authors have studied Kura-Araxes pottery obtained from the excavations of Tapeh Kelar site based on petrographic method.
This research is based on two questions. The first question of this research is that according to the minerals in Kura-Araxes and Middle Bronze Age pottery, what are the similarities or differences between them? And the second question includes the question that based on the petrographic study of the pottery samples of Tapeh Kelar, which of the ideas on how to spread the Kura-Araxes culture can be considered more logical for the emergence of this culture in the site? Based on visual evidence and cultural materials that show major changes in the transition from the Late Chalcolithic period to the Early Bronze Age, it can be expected that major changes have occurred in the field of process of pottery making and heating.
Discussion
In this study, 15 sample of potsherds obtained from excavations at Tapeh Kelar were selected. Samples were selected from Early Bronze Age (Kura-Araxes) and Middle Bronze Age contexts. Of these, 10 samples belonged to the Early Bronze Age and 5 samples belonged to the Middle Bronze.
10 samples of the Early Bronze Age were selected for the study. Samples can be divided into two main categories based on texture: samples with porphyry (coarse-grained) texture and samples with silty (fine-grained) texture. 9 samples have porphyry and coarse-grained texture and only sample number 4 has silty texture. 5 samples of pottery belong to the Middle Bronze Age. The samples have a dark background and a dark color.
Two types of silty tissue (samples 2, 4 and 5) and porphyry can be seen in the samples. Minerals detected in the samples are: quartz (clear and cloudy), plagioclase, amphibole and pyroxene, iron oxide, mica, Intrusive and extrusive volcanic rocks, silt and shale, chalcedony, agate and nepheline.
In the studied samples, some minerals are interesting. Nephline is rare in Iran. In Iran, due to the scarcity of alumina and other items that required nepheline, this mineral was importef from other countries due to its scarcity. Since the 1960s, several sources of nepheline have been reported in the northwest, such as Kalibar, Razgah, Bozqush, and Azarshahr.
Two other regions, namely the north of Shahroud and the central Alborz region, also have this mineral. In the north and northeast of Shahroud city in the Sultan Meidan area, the presence of nepheline mineral has been reported. However, due to the fact that the spread of Kura-Araxes culture was not to Shahroud city, the existence of Shahroud nepheline mineral has no role in the subject of this article. The third region, which is the central Alborz, is important in two ways: first, this mineral has been reported in it, and second, the Taph Kelar site is also located in the same region. As mentioned, in the geological map of Marzanabad sheet, the existence of nepheline mineral is mentioned.
Conclusion
The results of this study, as well as studies conducted elsewhere; show that each region has a regional diversity that itself indicates the local production of Kura-Araxes pottery. If that Kura-Araxes pottery was produced in one or more workshops in the motherland of the culture and then shipped to other areas, these potteries should not be so different and heterogeneous.
Nevertheless, two points should be considered: First, the studied site (Tapeh Kelar) may not be the oldest Kura-Araxes site in Alborz. In addition, ripple in the stream theory must be considered. The time difference between the region of origin of culture and distant regions has lasted for more than two hundred years.
In this theory, the spread of Kura-Araxes culture has been gradual and in several waves and stages, so it is possible that this expansion, even if it is due to migration from the Caucasus, is different from the Caucasus region in terms of mineralogical structure. This study shows that long-distance and direct exchange in the spread of Kura-Araxes culture to the Kelardasht area is not approved.
For better results, it is necessary to obtain more information, especially in archaeological site that transition from the Late Chalcolithic period to the early Bronze Age is uninterrupted, and also genetic studies on human remains of such sites to genetic changes in the inhabitants of the areas in the transition from the Late Chalcolithic Period to the Early Bronze Age Evaluated.
Amin Allah Kamali, Mohammad Hossein Azizi Kharanaghi, Syed Iraj Beheshti, Ali Aarab,
year 9, Issue 32 (8-2025)
year 9, Issue 32 (8-2025)
Abstract
Abstract
The slag sites under study are located in Khatam County, Yazd Province. In the archaeological surveys of Khatam County in 1400 AH, twelve metal smelting sites were identified through abundant metallic slag, and each of these sites was sampled. Petrographic analysis revealed that the predominant slag is iron, with only one instance of copper slag. The sites where metal smelting occurred, attributed to historical and Islamic periods based on pottery, exhibited evidence of iron smelting and its compounds in eleven samples. These samples contain metallic minerals such as wustite, marcasite, hematite, and magnetite. Marcasite and wustite minerals are related to smelting furnace processes and are products of mineral substances. It appears that in some mines in the region, magnetite and hematite are the predominant minerals, while in others, hematite is the predominant mineral, with a smaller amount of magnetite, which is evident in these primary minerals within the slag. Another sample related to copper slag exhibited small vesicular structures and limited copper ore minerals (chalcopyrite, digenite, and metallic copper) within the slag matrix. Alongside these primary minerals, there is a flow-like green glassy component indicating high furnace heat. The analytical results show that the MgO content in the samples is less than the amount of lime. Therefore, the limestone in this area is mainly ordinary limestone and not dolomite. Chemical analysis revealed that metal workers in this area were more successful at producing sponge iron.
Keywords: Archaeological Survey, Slag, Iron, Ancient Mining, Khatam.
Introduction
Iran has long been recognized as a center for mining and metal smelting. Archaeological evidence indicates that northern and central Iran are among the oldest centers of metallurgy in the world. The presence of rich mineral reserves in Iran, among other factors, has influenced the growth of mining and metalworking in this region (Momenzadeh, 2005). Due to the existence of various metal ores and advanced cultures in Iran, this area can be identified as one of the main hubs of technological innovation in the field of ancient mining and metalworking. Khatam County, located in the southern part of Yazd Province, holds particular significance in the realm of iron slag. One of the earliest efforts to produce steel worldwide took place in this region (Alipour et al., 2021). Considering the evidence of steel production in this area, it is essential (Alipour, 2017) to understand the role Khatam played in iron production during the Islamic and Sassanian periods. To investigate this matter, 12 sites in Khatam County were selected for studying iron slag. The main objective of this research includes petrographic and geochemical analysis of the slag to identify the type of extracted metal(s) and the extraction process and production of metal(s) at these sites. Additionally, the provision of necessary minerals for mining in this area is also under scrutiny. Historical and field research methods were employed for this study, involving the collection of data and archaeological investigations; field studies, such as topographic mapping, photography, identification of sites and metal smelting furnaces; and examination of samples using polarizing microscopes and XRF devices. This research has addressed primary inquiries related to the type of metals in slag, the mining process, and metal production at Khatam’s iron slag sites. Overall, Khatam County held significant importance in the production of metals during ancient and Islamic times. This region is recognized as one of the ancient mining and metalworking centers, and further research into the history and mining processes in this area could provide additional insights into the history of metalworking in Iran.
Discussion
Based on XRF chemical analyses of the slag, the results indicate that the majority of the mineral content in these slags consists of iron ore, with only one case showing the presence of copper. The CaO concentrations in these slags range from 3.59 to 28.41%, and an increase in CaO leads to the production of calcium-rich olivine. The type of slag (flow, permeable, massive, or furnace bottom) significantly impacts the results of chemical analysis and the ratio of oxides of the main elements (metallic oxides and silica). Additionally, the high amount of CaO facilitates the formation of a calcium-rich silicate phase. Petrographic microscopy studies confirm these findings, revealing observable olivine phases and primary silicate phases with metallic iron minerals such as magnetite and hematite. Due to the silica content, the addition of limestone to the smelting process increases the amount of duplex iron (Fe3O4). Consequently, silica stabilizes triplex iron oxide (hematite), while limestone stabilizes spinel iron oxide (magnetite). Moreover, microscopic examinations primarily reveal metallic minerals such as magnetite and metallic iron. Furthermore, sponge iron, like many other ancient civilizations in the region under study, was produced. The production of this type of iron requires less technical knowledge than other types of iron (Abbasnejad, 2009).
Surveying the region revealed that plants such as pistachios and wild almond produce high-quality charcoal. Since blacksmiths have no idea about using additional limestone in the furnace, the smelted slags were highly adhesive, leading to significant iron loss. The use of limestone in iron removal creates slags with fine properties that are easily separated from the iron (Abbasnejad, 2009). A good slag resulting from smelting should contain 30 to 40% limestone. Tests conducted on iron ore in this region show limestone percentages ranging from 3.59 to 28.41%. The slag analysis results also indicate a small amount of limestone, averaging approximately 11.38%. The deficiency of these two elements in slag, as they play crucial roles in reducing smelting heat and separating iron from slag, can indicate high iron levels and the inadequacy of slag (adhesiveness, viscosity, high density), resulting in low-quality sponge iron. The percentage of Fe2O3 ranges from 23.20 to 74.25%, and the percentage of Al2O3 ranges from 0.003 to 0.94%. The percentage of MgO in the tested slags is less than 0.003%. According to the mineral analysis, the most important iron minerals in this region include hematite (Fe2O3) and magnetite (Fe3O4). Due to technical flaws in these furnaces, sponge iron contains impurities such as silica, phosphorus, aluminum oxide, manganese oxide, and other metallic oxides, as confirmed by various tests conducted on ore and slag.
Conclusion
Eleven samples from the metal smelting site showed evidence of iron smelting and its compounds. In these samples, metallic ores such as wustite, marcasite, hematite, and magnetite are observed. Marcasite and wustite ores are related to smelting furnace processes and are mineral byproducts. It seems that in some mines in the region, magnetite and hematite are predominant, while in others, hematite is less prevalent, and magnetite dominates. Additionally, in the sample related to copper smelting slag, small and limited vesicles of copper ores (covellite, digenite, and metallic copper) are observed alongside a part of the green glassy matrix, indicating high furnace heat. This primary mineral evidence is observed in the slags. Considering the changes in the calcium oxide (CaO) concentration, it can be inferred that this substance was added during smelting operations to aid in smelting and reduce the temperature of the furnace materials. The microscopic results of some slags reveal primary minerals, mostly hematite and magnetite metallic ores, indicating a magmatic origin for the utilized minerals. The percentages of silica (SiO2), magnesium, and aluminum in these slags are relatively low. Analyses of these slags and iron stones from this region show that a deficiency of CaO and SiO2 leads to iron loss in the slag while increasing the iron content within it.
Based on this research, it is likely that iron ore was extracted from mines near the site and was subsequently transported to this location. Given the presence of iron mines at distances of 8, 10, and 15 kilometers from these sites, these mines are likely the source of these slags. Regarding the archaeology of the region, historical references indicate that the area held significance and prominence in various historical periods, particularly during historical and Islamic eras. However, due to insufficient information about the archaeology of the region and the lack of precise dating of these sites, accurate dating of these sites is unfeasible.
The slag sites under study are located in Khatam County, Yazd Province. In the archaeological surveys of Khatam County in 1400 AH, twelve metal smelting sites were identified through abundant metallic slag, and each of these sites was sampled. Petrographic analysis revealed that the predominant slag is iron, with only one instance of copper slag. The sites where metal smelting occurred, attributed to historical and Islamic periods based on pottery, exhibited evidence of iron smelting and its compounds in eleven samples. These samples contain metallic minerals such as wustite, marcasite, hematite, and magnetite. Marcasite and wustite minerals are related to smelting furnace processes and are products of mineral substances. It appears that in some mines in the region, magnetite and hematite are the predominant minerals, while in others, hematite is the predominant mineral, with a smaller amount of magnetite, which is evident in these primary minerals within the slag. Another sample related to copper slag exhibited small vesicular structures and limited copper ore minerals (chalcopyrite, digenite, and metallic copper) within the slag matrix. Alongside these primary minerals, there is a flow-like green glassy component indicating high furnace heat. The analytical results show that the MgO content in the samples is less than the amount of lime. Therefore, the limestone in this area is mainly ordinary limestone and not dolomite. Chemical analysis revealed that metal workers in this area were more successful at producing sponge iron.
Keywords: Archaeological Survey, Slag, Iron, Ancient Mining, Khatam.
Introduction
Iran has long been recognized as a center for mining and metal smelting. Archaeological evidence indicates that northern and central Iran are among the oldest centers of metallurgy in the world. The presence of rich mineral reserves in Iran, among other factors, has influenced the growth of mining and metalworking in this region (Momenzadeh, 2005). Due to the existence of various metal ores and advanced cultures in Iran, this area can be identified as one of the main hubs of technological innovation in the field of ancient mining and metalworking. Khatam County, located in the southern part of Yazd Province, holds particular significance in the realm of iron slag. One of the earliest efforts to produce steel worldwide took place in this region (Alipour et al., 2021). Considering the evidence of steel production in this area, it is essential (Alipour, 2017) to understand the role Khatam played in iron production during the Islamic and Sassanian periods. To investigate this matter, 12 sites in Khatam County were selected for studying iron slag. The main objective of this research includes petrographic and geochemical analysis of the slag to identify the type of extracted metal(s) and the extraction process and production of metal(s) at these sites. Additionally, the provision of necessary minerals for mining in this area is also under scrutiny. Historical and field research methods were employed for this study, involving the collection of data and archaeological investigations; field studies, such as topographic mapping, photography, identification of sites and metal smelting furnaces; and examination of samples using polarizing microscopes and XRF devices. This research has addressed primary inquiries related to the type of metals in slag, the mining process, and metal production at Khatam’s iron slag sites. Overall, Khatam County held significant importance in the production of metals during ancient and Islamic times. This region is recognized as one of the ancient mining and metalworking centers, and further research into the history and mining processes in this area could provide additional insights into the history of metalworking in Iran.
Discussion
Based on XRF chemical analyses of the slag, the results indicate that the majority of the mineral content in these slags consists of iron ore, with only one case showing the presence of copper. The CaO concentrations in these slags range from 3.59 to 28.41%, and an increase in CaO leads to the production of calcium-rich olivine. The type of slag (flow, permeable, massive, or furnace bottom) significantly impacts the results of chemical analysis and the ratio of oxides of the main elements (metallic oxides and silica). Additionally, the high amount of CaO facilitates the formation of a calcium-rich silicate phase. Petrographic microscopy studies confirm these findings, revealing observable olivine phases and primary silicate phases with metallic iron minerals such as magnetite and hematite. Due to the silica content, the addition of limestone to the smelting process increases the amount of duplex iron (Fe3O4). Consequently, silica stabilizes triplex iron oxide (hematite), while limestone stabilizes spinel iron oxide (magnetite). Moreover, microscopic examinations primarily reveal metallic minerals such as magnetite and metallic iron. Furthermore, sponge iron, like many other ancient civilizations in the region under study, was produced. The production of this type of iron requires less technical knowledge than other types of iron (Abbasnejad, 2009).
Surveying the region revealed that plants such as pistachios and wild almond produce high-quality charcoal. Since blacksmiths have no idea about using additional limestone in the furnace, the smelted slags were highly adhesive, leading to significant iron loss. The use of limestone in iron removal creates slags with fine properties that are easily separated from the iron (Abbasnejad, 2009). A good slag resulting from smelting should contain 30 to 40% limestone. Tests conducted on iron ore in this region show limestone percentages ranging from 3.59 to 28.41%. The slag analysis results also indicate a small amount of limestone, averaging approximately 11.38%. The deficiency of these two elements in slag, as they play crucial roles in reducing smelting heat and separating iron from slag, can indicate high iron levels and the inadequacy of slag (adhesiveness, viscosity, high density), resulting in low-quality sponge iron. The percentage of Fe2O3 ranges from 23.20 to 74.25%, and the percentage of Al2O3 ranges from 0.003 to 0.94%. The percentage of MgO in the tested slags is less than 0.003%. According to the mineral analysis, the most important iron minerals in this region include hematite (Fe2O3) and magnetite (Fe3O4). Due to technical flaws in these furnaces, sponge iron contains impurities such as silica, phosphorus, aluminum oxide, manganese oxide, and other metallic oxides, as confirmed by various tests conducted on ore and slag.
Conclusion
Eleven samples from the metal smelting site showed evidence of iron smelting and its compounds. In these samples, metallic ores such as wustite, marcasite, hematite, and magnetite are observed. Marcasite and wustite ores are related to smelting furnace processes and are mineral byproducts. It seems that in some mines in the region, magnetite and hematite are predominant, while in others, hematite is less prevalent, and magnetite dominates. Additionally, in the sample related to copper smelting slag, small and limited vesicles of copper ores (covellite, digenite, and metallic copper) are observed alongside a part of the green glassy matrix, indicating high furnace heat. This primary mineral evidence is observed in the slags. Considering the changes in the calcium oxide (CaO) concentration, it can be inferred that this substance was added during smelting operations to aid in smelting and reduce the temperature of the furnace materials. The microscopic results of some slags reveal primary minerals, mostly hematite and magnetite metallic ores, indicating a magmatic origin for the utilized minerals. The percentages of silica (SiO2), magnesium, and aluminum in these slags are relatively low. Analyses of these slags and iron stones from this region show that a deficiency of CaO and SiO2 leads to iron loss in the slag while increasing the iron content within it.
Based on this research, it is likely that iron ore was extracted from mines near the site and was subsequently transported to this location. Given the presence of iron mines at distances of 8, 10, and 15 kilometers from these sites, these mines are likely the source of these slags. Regarding the archaeology of the region, historical references indicate that the area held significance and prominence in various historical periods, particularly during historical and Islamic eras. However, due to insufficient information about the archaeology of the region and the lack of precise dating of these sites, accurate dating of these sites is unfeasible.
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