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Long-term environmental effects of Roman mining in the Plasenzuela silver-lead district of Extremadura, Spain

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Project overview

A small but vigorous Roman mineral industry in a lesser Spanish silver-lead mining district has left a legacy of contamination of soils and river alluvium by the mining and smelting wastes that continues to this day. Field studies completed on this project have confirmed suspected excessive heavy metals (such as lead and zinc) in (1) Roman slags and associated soils, (2) mine waste rock dumps thought to be Roman, (3) alluvium of the Rio Tamuja (as much as 20 times background amounts of lead and zinc), and (4) widespread lead-rich soil patches that may have been contaminated by fumes from the Roman smelters.

Verification of the age of the mine dumps and substantiation of the suspected smelter plume provides exciting new benchmarks for judging the persistence of mineral industry wastes in the environment over very long periods. Most details of the mining and metallurgical process used at this site remain unknown, though they have certainly influenced the type and distribution of contaminants. The project concentrated on verification of the smelter plume and of the age of mine dumps, and sought a better understanding of the entire industrial process from mine to finished product.