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 . 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.
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.
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.
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