Georgius Agricola, Latin name of George Bauer (1494-1555), German mineralogist and metallurgist. His De Re Metallica (on the Nature of Metals) is a detailed record of 16th century mining procedures and the related sciences. Agricola describes the types and design of the smelting furnaces used in the process of extracting base metals from the ore. He described it as ?皜??rfecting metal by fire?? Agricola drew attention to the health hazards (known since the Geeks) associated with metal working; recent examination of slag (the waste matter of smelting ) from the area of a medieval metallurgical workshops revealed high levels of heavy-metal contamination.