About the 18 slags that were analyzed, they were collected in a surface context labelled “Transectos”. This context is characterized as being a horizontal plane area, which is located the south-east zone of the top of the hill, and to the west, it’s around 45 meters from the main mound of the site. The collecting technic used for recovering the slags in the ground was transects, which had the task of collecting every slag piece in sight.
After the slags were collected the samples were analyzed by archaeometry’s technics such as Optical Microscope (OM), X-ray Fluorescence (XRF) and Scanning Electronic Microscope (SEM), generating data that aided in the characterization of the technology that was used by the metallurgists of Jicalán Viejo. Thus, those analysis also were very helpful for answering questions related to the ores used, about the process of reduction and some clues about the possibles mines from which the minerals were extracted, suggesting by the latter, that the mining routes depicted in the Lienzo of Jicalán could match with the archaeological record, nevertheless, more data is necessary for validating this idea.
Consequently, by the analysis of the data obtained by the archaeometry’s technics, the research found out a primary reducing activity was carried out in Jicalán Viejo, and the technology that was used was a slag-tapping furnace which characterized in reaching temperatures between 1100-1200°C and could maintain an atmosphere with reducing conditions capable of reducing sulphidic copper ores. The analysis also provided information about the behavior of the metallurgists of Jicalán Viejo, which summarized that the metallurgists of the site were conscious with the activity of smelting and had some control of the process. Additionally, the presence of arsenic in some of the metallic phases can suggest that sometimes the ores rich of arsenic, for example, arsenopyrite, could be mixed with the sulphidic copper ores, like chalcopyrite, suggesting the possibility that the metallurgists of Jicalán Viejo had a knowledge of arsenical bronze alloy.
Finally, by taking into account the ores arsenopyrite and chalcopyrite, was possible to distinguish some mines that contain those two ores, and which are located in the area of the eastern route depicted by the Lienzo of Jicalán, but this is a very light assumption which needs more data and research to validate this idea.
Conclusions:
These results have shown us a small sample of everything that can be learned through the slags, the reduction disposals. Thus, we can agree with Craddock (2000:152) that the slags are the main indicator of smelting activities, because, following Charlton et al. (2010:354), slags make evident the individual receipts of each smelting process. Finally, is necessary that the data obtained from this context must be used for comparing the data from the other contexts of the site where has been identified slags because by this methodology will be possible a better understanding of the site and its copper production.\
Acknowledgements
I thank the Consejo Nacional de Humanidades, Ciencias y Tecnologías (CONAHCYT) before CONACYT), to all the members of the project Preindustrial Mining and Metallurgy in Mexico: Research on Copper Smelting in Michoacán and to the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), who without their support this research would not have been possible.
Contact: Andrés Francisco Sánchez Guerrero
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