text: By the 14th century, the majority of the more easily accessible ore deposits were exhausted. Thus, more advanced technological achievements were introduced in order to keep up with the demand in metal. The alchemical laboratory, separating precious metals from the baser ones they are typically found with, was an essential feature of the metallurgical enterprise.
  A significant hiatus in underground mining was noted during the 14th and the early 15th century due to a series of historical events with severe social and economic impacts. The Great Famine (1315–1317), the Black Death (1347–1353), which diminished the European population by one third to one half, and the Hundred Years War (1337–1453) between England and France, that, amongst others, caused severe deforestation, and had dramatic influences in metallurgical industry and trade.
  Lead mining, for example, ground to a halt due to the Black Death pandemic, when atmospheric lead pollution from smelting dropped to natural levels (zero) for the first and only time in the last 2000 years. The great demand of metals, e.g. for armor, could not be met due to the lack of manpower and capital investment.
  It was only by the end of the 13th century that great capital expenditures were invested and more sophisticated machinery was installed in underground mining, which resulted in reaching greater depths. The wider application of water and horse power was necessary for draining water out of these deep shafts. Also, acid parting in separating gold from silver was introduced in the 14th century (Bayley 2008). Signs of recovery were present only after the mid 15th century, when the improved methods were widely adopted (Nef 1987, 723).
  The discovery of the New World had an impact on European metal production and trade, which has affected the world economy ever since. New, rich ore deposits found in Central Europe during the 15th century were dwarfed by the large amounts of precious metal imports from the Americas.