They did in Mexico, but in South America, it was cheaper to use indigenous labor. Purchasing slaves was inefficient because, one, they didn't have experience working at high altitudes, and two, mine work was super deadly. Mercury, which can be used to refine silver ore, was found at the mountain of Juan Cavalica. And mercury poisoning among miners was so common that parents would often maim their children to keep them from having to work in the mines. You can see why I'm struggling to be festive. Let's go to the Thought Bubble. So Spanish mines in the Americas produced over 150,000 tons of silver between the 16th and the 18th centuries, over 80% of the world's supply.