Newswise — Russian scientists studied artefacts from cultural layer of the Vorovskaya Yama mine, situated in the Chelyabinsk region, and found out that there, apart from ore production, people made metalworking. About 1500 years BCE masters melted out products from copper and tin bronze. More likely scales of manufacturing were limited. The research is published in Russian archeology journal.
Vorovskaya Yama is a copper mine situated in the steppe zone of South Trans-Urals. It is a large rounded career of 4-5 meters depth and with diameter of 40 meters. In 2021 archeologists found ruined remains of some buildings with hearths inside. Results of the radiocarbon dating enabled to state that constructions belonged to the Late Bronze Age and existed in the period of 1600-1500 cal BCE.
This is the unique complex of that kind in the mines of Alakul culture, that existed in the first half of II millenium BCE. It was spread in steppe and forest-steppe belt of South Trans-Urals, West Siberia, North and Central Kazakhstan. These people lived on complex cattle breeding, the main branches of economics were metallurgy, pottery and bone-carving, tanning and textile production. Scientists from South Ural State humanitarian and pedagogical university, South Ural Federal Research Centre of Mineralogy and Geoecology of Ural Branch of RAS and Institute of History and Archeology of Ural branch of RAS decided to find out if discovered in Vorovskaya Yama fireplaces and ceramics belonged to metal production. This information will help to understand social organization of miners’ labor and reconstruct their technologies.
Archeologists studied three groups of findings: samples of soil from filling of four hearths, six fragments of ceramics with traces of high-temperature exposure and one fragment of metallurgical slag.
Nowadays from hearths remained layers of specific soil of red and chestnut hints with ash and fragments of charcoal. Having analyzed their composition, scientists suggested that their shapes could repeat outlines of ground single-cell hearth. During investigation of one of the objects scientists noticed clear underlying layer of small stones. Obviously, it evened the bottom of the hearth and protected it from cold and wet.
Scientists conducted X-ray fluorescence analysis of soil from the hearths. In total they took 24 samples of soil from 12 different layers of objects. The analysis showed rather high content of copper – in average 0.6 mas.%. Such figures in general are characteristic of cultural layers of settlements at the mine, because they contain in large volume fragmented copper minerals – malachite and azurite. However soil from one of the hearths contained much more alloy of copper (up to 2mas.%) and also trace contents of tin, that enabled to suggest its use in metal production.
Another important category of findings was ceramics. Selected samples differed from other fragments of vessels found in abundance at the mine by traces of high temperature exposure. Some things were marked by foamed surface - it was rough, saturated with micropores and minerals with changed structure. Archeologists analyzed six fragments of different vessels: one rim, one shoulder, three bodies and one bottom. Most likely some of ceramic products were used as melting pots for ore processing or form in that miners poured bronze ingots. Slagging on vessels could occur as a result of smelting of metal from ore or by remelting of finished products.
Then scientists made the analysis of metal slag. It was found beyond these buildings of mine, that were studied by archeologists. Low-silicon glass became the basic mass of slag, and metals were presented in it by copper drops with alloys of iron and nickel. Scientists suggested that near mine workings ancient people both mined copper ore and produced copper and bronze from it.
This and other samples of slag – products of melting of pure copper minerals with rare alloys of iron and nickel. Glass and minerals contained a large volume of zinke alloy, that is characteristic of this deposit. It shows that miners dag for ore exactly there. The occurrence of mineral chalcocite and copper drops says about the fact that masters used secondary sulphides.
However, signs of wide-scale melting of metals from ore in the studied part of miners’ village were rather poor. There are much more evidences of remelting: according to archeologists, as a minimum one hearth was used for melting of ingots and remelting of finished copper and tin-containing products. Features of structure of another fireplace point to the fact that it could be used in metal production too: characteristic oval form of core with break for air-duct channel, its small size, enamel with little stones and absence of even tiniest fragments of slag.
Thus, ancient miners near copper deposit Vorovskaya Yama made metal working, although not very actively. Most likely they satisfied their own needs in production of mine development tools from copper and bronze. In order to do this, they used melting ceramic bowls and thermotechnical facilities- hearths, from which now remains colorful spots. In future archeologists will prove their hypothesis about scales of metallurgy at mines and settlements of late Bronze Age.
The material is prepared with the financial support of the Russian Ministry of Education and Science within the framework of the federal project "Popularization of science and technology".
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