Abstract
The mineralogical and chemical investigation of ancient slag is of high importance for economic mineralogist and archaeometalurgist. These investigations reveal information, which is of general historical and mineralogical interest. Over than 95% of metallic reservoirs have proved antiquity evidences. By using mineralogical-petrographical studies on metallurgical slag as an object from the ancient world, it could be enhance to understanding about the major and trace elements via metal extraction.
The basin of Halil Rood (Halil River) is privileged to have a rich civilization. Many objects as well as metallurgical evidences belonging to the third millennium BC have been discovered in this district during the archeological excavations. Kerman – Rabor – Jiroft district is of great interest due to the archaeometallurgical signs in south-west Iranian desert and belong to the Halil Rood region. This district is important according to the enrichment of polymetallic hydrothermal ore reservoir such as Cu, Pb, Zn, Sn, Ag and Au in south and south-west of Zagros orogeny. Several scientists have been focused on this region, as one of the born place of metallurgy in the ancient World [1]. The primary aim of this study was the characterization of extracted metals and the methods of smelting. The objects to be discussed here are mostly copper slag as well as ores. 20 local mining- and metallurgical places have been found through recently archaeometallurgical expedition. These places are mainly consisted of slag-heap, fireplaces and ore deposition, which are remarked possibly as passage-metallurgy along south Iranian desert.
Keywords: Archaeometallurgy, Metallogeny, Petrology, Slag, Copper, Kerman.

Introduction
There are several slag accumulations in Halil region. The slag samples investigated during the present work were collected from thirty-seven different ones which were located in different parts of studied area. There are four Types of slags in these districts districts.
A) The slags are generally massive and in some cases the colour is black with some red spots (Copper). The sign of flow structures can be seen on some of them, but there is no glacial one. The porosity is high as well as their density. The structure such as furnace has been excavated from this area. This Furnace has ca. 1.5 m cross section dimension.
There was a deponie of slags materials upside this furnace. In the furnace there exist no slags by now. It could be the furnace with temporary employment in this region. Such furnaces with the same structures have been observed in the north of central desert in Iran, In sahroud and Khorasan region.
B) there are five small dumps located near each other which have been considered. These samples have flow structures. They are black and red in color and have more porosity than an accumulation’s samples.
C) several small dumps located at the main stream at the north of Rabor-Jiroft district, which considered as C accumulation. Only one slag was selected from it. This sample is black in colour and has massive structure. No flow or glacial structures can be seen between slag pieces in C accumulation.
D) A very small dump has been excavated. The physical properties of these slags are completely different from other ones. This sample has many porosity and low density. It is black in colour and no flow or glacial structures are seen. Mineralogical and petrological analyses were performed only on slag materials. The dating of all this samples to classify these dumps could not be possible in this project. The distribution of the dumps is not only statistically but also commonly on this field, and for this reason there is another factor to have no chance to get the better results in respect on the ageing of dumps on this region exactly. The topographic situation and the changing of the earth in each seasons, and the movement of the seasonal rivers disturb the structure of the surface topography permanently each year. This distribution during the overflows in the wet seasons could be the aspect of slag’s distribution either.

Halil region is located in south central of Iranian metallogenic zone. Rock types in this area are mainly divided into 6 sections as follow:
1. Upper Proterozoiec: the oldest and the most abundant rock type in studied area. This formation is composed of quartzitic shist, phyllic- like schist, green schist and marble. Quartz-chloric, quartz- seresic, chloritic schist are also existed with an admixture of carbonate with thick layers and lenses of dolomitize marble, dolomite and rare beds of chloritized calcareous-quartz.
2. Cretaceous: This rock type forms bands of sublatitudal. Lower Cretaceous deposits are spread in external parts. This rock type largely composed of carbonate rock, less abundant conglomerate, gravels and sand stone.
3. Eocene: This basal unit of tuff- conglomerate lies completely at the lower part of the complex. These are overlain by tuff and lavas of trachyandesitic and andesitic composition, with intercalation of trachyandesite- basalt and lime stone. The section is crowned by fine- fragment of tuff and tuff- mudstone.
4. Dykes: the oldest and the most abundant Dykes are porphyry granite, aplitic granite, microgranosyenite, syenite and lamprophyre. The younger ones are porphyry granodiorite and porphyry diorite.
5. Plutonic rocks: these rocks are very abundant and most of them are acidic. Linear ultra mafic structures are observed in this area. Plutonic units are divided into different parts: Diorite-Manzanite, Manzanite-Quartz Manzanite, Porphyry Alkaline, Graniteporphyry, Quartz Syenite.
6. Quaternary: these sediments are widespread in all over the studied area. Genetically, they are subdivided into alluvial- proluviall- and eolian sediments.
The probable ore types which is outcropped in this area are classified as the following table; The objects to be discussed here are the copper slag. The primary aim of this study was the characterization of materials and the methods of smelting. The objects which have been found here are mostly slag as well as ores. The slag shows the structure of casting slag and also remains from the smelting furnace. The materials are characterized by means of XRD-XRF and Pol-Microscopy methods.

Conclusion
The slag contains high amount of Copper oxide, hydroxide and carbonate and silicate and some amount of MgO or MnO complexes. The main silicate appeared here is Fayalite and pyroxene which has been existed in the matrix of slag. The main paragenesis is chalcocite-chalcopyrite-covellite. copper was smelted at the high oxygen fugacity; approximately about 10-7 atm. Indeed, the furnaces heated with charcoal and charcoal observed also in the macroscopic texture of slag.

References
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Abstract
Lut desert is located in southeastern Iran. The area, despite having many historical monuments, including numerous castles, has not received enough attention from architectural historians. This study aims to clarify the architectural features and the purpose for the multiplicity of these fortresses in this region, it has been tried to study and investigate them with descriptive, analytical, and logical cognitive methods. The research was carried out by library and field studies of 140 castles, as case studies, in the region. The study’s results show that the climate and security factors are the main reasons for erecting the castles. Abundant water and location on the trade routes made the region rich, and on the other hand, point water sources and their limitations caused dispersion and distance between the structures and increased insecurity. According to historical sources, desert outlaws have also had a large presence in the region.  Besides, the techniques to deal with violent sandstorms had caused them to build cities and villages in the middle of high barriers, or to build a castle inside or around it for use in times of need, which caused the number of castles in the investigated area. This has also caused the majority of castles in the region to have residential functions and be built inside or around cities and villages, and other functions and establishments are less frequent. The architecture of the castles and defense fortifications of the region also follows the common architecture of the central plateau castles, excluding incomparable cases. So, most of the castles follow the square and rectangular geometry, and in some cases, the irregular, trapezoidal, and parallelogram geometry is derived from the climatic and contextual conditions. The materials used were canvas and due to the ease of construction, speed of mass production, lower cost and camouflage, mud and mud brick in plain fortresses, and stone in mountain ones. Most of the towers are built in the corners and the middle of the sides with observational, defensive, and structural functions, and in some cases, towers are seen in the middle of the castle with only observational functions. The fortresses’ defense structure mainly is based on the barrier and tower, and as the wealth and population of residential castles increased, more defense boundaries were added.
Keywords: Fortress, Defensive Fortifications, Lot Desert, Kerman.

Introduction
Castles were military or civilian fortifications that were built using natural geographical features to maintain security (Sultani Mohammadi and Bulouri Bunab, 2015: 75). There are many variations in their use and they have a form of residence and social structure, different from the structure of the village and city (Parsi, 1383: 136; Nurbakhsh, 1366: 147).
In Iran, the formation of enclosed group buildings with various methods has a history of three thousand years (Kleiss, 1383: 160). The early forts in Iran can be seen as a relic of the agricultural civilization, when humans started to settle down and needed to maintain their security (Kiani, 1374: 78). In the past, next to many settlements and cities of Iran, there were one or more fortresses, which became people’s shelters during unrest and insecurity (Pirnia and Me‘marian, 2007: 82). Their functions were different, and the smallest of them was a military base or post, and the largest of them were guarded shelters for caravans and military and defensive forts (Siro, 1357: 54). Also, some of them were the central core of the ancient cities of Iran, and the main life of the people was often formed inside the fortresses and old forts (Zarei and Heydari Baba Kamal, 2016: 202). Some scholars believe that castles were built first and then towns were formed around them (Zuka, 1374; Na‘imi, 1389). These defense structures were usually built by the governments to protect the strategic and border cities against the enemy’s invasion and the encroachments of nomadic desert rovers (Wiley, 2016: 26).
Owing to political, economic, and geographical requirements, in both pre-Islamic and Islamic eras, numerous fortresses, and defensive buildings were built. The southern and western edge of the Lut desert in Kerman province is one of them, due to its special geographical location, has many historical castles that have not been studied and investigated in detail, and the studies conducted are limited to archaeological investigations and identifications and monographs. It is related to buildings. This area consists of important cities such as Ravar, Shahdad, Bam, Fahraj, Regan and Narmashir. Each of these cities had political, social and economic prestige at some point in history from the third and fourth millennium BC to the middle Islamic centuries (Qazvini, 1373: 243; Muqadsi, 1361: 680 and 684; Istakhari, 1373: 246; Yaqut, 1383: 269 and 296; Zarei and Heydari Kamal, 1393: 196, Hakimi, 1385: 28; Hakeimi, 1351: 78; Kabuli, 1369: 213). Considering the importance of this type of building in understanding the historical architecture of Iran, as well as the process of their destruction due to natural and human erosion, it is necessary to examine them with a closer look and in more detail. The upcoming research has investigated the castles of this area with such an approach and tried to answer two main questions: 1- What are the architectural characteristics of the fortress in the geographical area of the southern and western border of the Lut desert? 2- What is the main reason for the appearance, formation, and number of fortresses in this region?

Discussion
The structure used in the barrier of all the load-bearing wall castles and the materials used in the fence of all the plain castles the mud and mud brick and mountain areas, stone and baked brick are used for strengthening the base of the barriers. Stone has been the main material in the few mountain castles in the region. Although various decorations are used in the castles, due to functional reasons, they are seen in a limited number.
In terms of shape, the majority of castles in the region are square and rectangular, that is, the dominant form of such buildings in the central plateau of Iran. However, there are several castles with special trapezoidal, parallelogram, and irregular geometries, which were built in this way due to the specific topography of the environment and climatic conditions, such as facing sandstorms.
The dominant form of the towers is also cylindrical. In some cases, rectangular cube forms and square bases have been used, all of which have led to more structural resistance of the towers. The semi-cylindrical form has also led to the optimal use of space. Only one case of a triangular tower foundation has been seen in the castles, which is considered an exception. In terms of the location of the towers, the majority are placed in the corners and middle of the sides, which is by the usual architecture of castles. However, the construction of towers in the middle of the castle is surprising in many cases.
The defense structure of the castles of the region is based on two types, fenced and unfenced. Most of them consist of walls and towers, and several fences and ditches have been added. In some cases, the position of the bed in the mountain castles has been used and, on some sides, the fence has been removed. Most of the castles are located inside or outside of villages and cities for security and climatic reasons. The forts on the road and near the rivers were also built for security reasons.
To determine the exact function of fortresses is unclear, however, based on the previous data, the purpose can be recognized to some extent. Therefore, the castles that were built at the critical points between the road and the water divide had military use in strategic locations. The fortresses that were built in the center and around the villages were the lords’ fortifications that had either a residential position or an economic function. In the case of expansion and adding spaces such as the guard’s room, posts, and spaces similar to the military function, they become residential and if they are located in a prosperous city and court spaces are located inside them, they have a ruler’s seat. Fortresses that are located next to villages and cities have a shelter function.  

Conclusion 
the research studied the architectural features of the fortifications and defensive structures of the western and southern border of the Lut desert from 5 aspects: construction method, defensive structure, form, location, and function. The results of this study show that the fence structure of all the castles under investigation of the load-bearing wall is mainly made of mud and mud bricks, and in some cases, stone and brick have been used in combination with them for more strength. The richness of mud and mud bricks, cheapness and lower construction expenses, riches of mass production, faster production, matching the color with the environment, and helping to better camouflage compared to bricks and non-woven materials. Also, few mountain castles are built with stone materials due to their availability and the possibility of camouflage. The defense structure of most castles is based on fences and towers, and the number of towers and fences has been reduced and increased according to demand, and moats have been used. In general, as the wealth and population of castles, one of whose functions was residential, increased, rulers and residents increased the number of defense layers. There is also a type without fence, which is built due to climate and derived from the form of nuclear villages. In this way, the height of the external walls was increased to prevent the entry of sand into the central structure, no doors and windows were opened to the outside, and the passage was made only through the gate. This is not only to deal with climatic problems but also increases the security of the castle. The dominant form in the castles of the region is square and rectangular, but due to climatic and contextual reasons, many rhombus-shaped, trapezoidal, and irregular castles have also been built. The castles built based on the plan, follow the traditional square and rectangular geometry of the castles of the central plateau of Iran. The castles that have expanded over time and the castles that have been designed using the characteristics of the bed and the background (such as mountain and riverside castles) have irregular geometry. Most of the towers are built in the middle of the sides and corners however, in some cases, the construction of towers is in the middle and outside of the fortress. The towers in the middle of the castle had only an observation role, but the towers located in the corners and the middle of the sides had a defensive and structural role. Also, due to structural and spatial reasons, some castles are made of rectangular cube towers, cube bases, and semi-cylindrical towers.
The number of castles in the region is affected by the forces of security and climate. The inhabitant areas of the western and southern border of Lut have been very rich due to plentiful water and are located on commercial roads. On the other hand, the limitation of point water sources such as wells, aqueducts, and springs had caused the creation of irregular and scattered villages in the middle of the desert with a distance from each other and increased insecurity. According to historical sources, desert outlaws have also had a large presence in the region. All these factors, in addition to the techniques to deal with violent sand storms, had caused cities and villages to be built in the middle of the fence, or to build a castle inside or around it for use in times of need, which has caused the number of castles in the investigated area.  This has caused the majority of fortresses in the region to have residential functions and to be built around and inside villages and cities, and other functions and settlements are less frequent.