Large-scale mining and smelting of specularite ores in the Altai mountains during the 1st millennium AD

According to past historical documents and archaeological evidence, the Altai, rich in iron ore deposits, was a major iron production region in Eurasia during the 1st millennium AD. The present article focuses on the investigation of the large specularite (specular hematite) deposit Rudny Log in the Southeastern Altai (Russian part), long time regarded as a potential mine for the 1st millennium AD iron smelters. To test this hypothesis, we use complex approaches combining: 1) spatial analyses and field recording of traces of workings found at the mine; 2) radiocarbon dating; 3) microstructural (by OM and SEM); 4) geochemical (by XRF and ICP-MS) and 5) multivariate statistical investigation of iron ore and slag samples found at the mine and seven major ancient iron smelting sites in the Southeastern Altai. The results of spatial analysis and fieldwork carried out at the mine reveal the presence of c. 350 pit workings from ancient exploitation, which can be estimated as c. 2500 tons of extracted ore. The radiocarbon analyses indicate the 1st-2nd c. AD timeframe to the start of the exploitation of the mine and the earliest iron smelting in the Southeastern Altai, which is likely linked to the Xiongnu expansion. The materials and statistical analyses allow us to preliminary identify Rudny Log, or, alternatively, another major deposit in the region, as the main source for five major iron production sites operated during the 1st millennium AD. Apart from that, the analyses suggest the exploitation of two currently unknown ore sources at three of the smelting sites. The significant scatter and remoteness of metallurgical centers from the mine can be associated with the nomadic subsistence of smelters who integrated seasonal metallurgical production with the search for new pastures and fuel resources.

Automated summary

Based on historical documents and archaeological evidence, the Altai region was a major iron production area in Eurasia during the 1st millennium AD. This study focuses on the Rudny Log deposit in the Southeastern Altai and suggests it as the main source for major iron production sites during that time.