I've heard a lot about the vast amounts of silver and gold that Spain brought back from the Americas. I imagine that they looted the Aztecs and other peoples at first, but silver/gold exports continued for a long time, so there must have been mines.
How were these mines operated? Particular in the days before machinery and explosives, this must have been very hard labor. How many people worked a mine and how was the ore extracted? How did they keep the mine from filling with water (either rainwater or groundwater)?
The time frame I'm interested in is 1500-1750, maybe 1800 max.