Summary

Rome came into possession of a wide variety of mineral resources as a result of imperial expansion. Large mines were opened up in many provinces, especially in the Iberian Peninsula, Gaul, Britain, the Danubian provinces, and Asia Minor. Pollution records show that the scale of mining in antiquity peaked during the Roman period and was not matched again until the Industrial Revolution. The main minerals exploited were gold, silver, copper, and tin, which were used to mint coinage. Lead was mined for pipes and other utilitarian purposes, while iron was used often for tools. The techniques and organization of mining varied by period and geological conditions. The most common techniques included opencast (open air) mining, underground (shaft-and-gallery) mining, and placer (alluvial) mining. While individuals and municipalities could own mines, mining districts (metalla) increasingly came under the control of the state. Concessions to work state-owned mines could be leased out to individuals, small associations, or larger societates who worked the mines and turned over a portion of their profit to the state. Mines could also operate under direct state control, as occurred in large-scale gold mining of the imperial period in north-west Spain. The operation of mines often relied on forced labourers, including enslaved workers, prisoners of war, convicts, and tribute workers. The army provided technical expertise and/or surveillance, while, in the imperial period, a procurator metallorum and other imperial officials administered mining districts. There is also ample evidence for free and freed wage labourers in mining districts, who were often economic migrants. Mining was essential to the Roman economy and has much in common with other extractive industries such as quarrying.