The extraction of silver and mercury in Spanish new world was central to the expansion and upkeep of the empire. Silver provided wealth enabling the crown to project power and pay its debts. In the early years of the conquest the Spanish pilfered and exhausted Inca gold and silver available in stores and caches. Eventually, the Spanish found deposits of gold and silver and developed a form of forced mine labor (mita) wherein indian families were required to provide a worker for one year’s unpaid labor in the mines.
The Viceroyalty of New Spain and the Viceroyalty of Peru during the age of conquest developed many mines, yielding mostly silver. Many deposits, especially Cerro Rico in what is now Potosi, Bolivia, contained silver in the metallic form to some minor extent. The Incas had developed smelting before the Spanish occupation, but the process was inefficient and required fuel for smelting. Wind smelting was developed by the Incas, but was dependent on the winds to drive the fires. The discovery of amalgamation and recovery of silver and gold by retorting solved many problems in production.
After the discovery of the patio amalgamation process in 1554 in what is now Mexico, the importance of mercury was recognized as the key to efficient, large scale silver production. This discovery eventually enabled the large scale enslavement of aboriginal peoples to run the mercury mines and smelters of Huancavelica, Peru, and amalgamation operations in the many silver mines in the region.
We found these kingdoms in such good order, and the said Incas governed them in such wise [manner] that throughout them there was not a thief, nor a vicious man, nor an adulteress, nor was a bad woman admitted among them, nor were there immoral people. The men had honest and useful occupations. The lands, forests, mines, pastures, houses and all kinds of products were regulated and distributed in such sort that each one knew his property without any other person seizing it or occupying it, nor were there law suits respecting it… the motive which obliges me to make this statement is the discharge of my conscience, as I find myself guilty. For we have destroyed by our evil example, the people who had such a government as was enjoyed by these natives. They were so free from the committal of crimes or excesses, as well men as women, that the Indian who had 100,000 pesos worth of gold or silver in his house, left it open merely placing a small stick against the door, as a sign that its master was out. With that, according to their custom, no one could enter or take anything that was there. When they saw that we put locks and keys on our doors, they supposed that it was from fear of them, that they might not kill us, but not because they believed that anyone would steal the property of another. So that when they found that we had thieves among us, and men who sought to make their daughters commit sin, they despised us.
Many Spaniards attempted to speak out for the Inca and other aboriginals. Few were effective. But by the time of the Fifth Viceroy of Peru, Francisco Alvarez de Toledo, it was recognized (by Toledo, at least) that reforms were needed to bring the Inca into Christianity and life in a world of laws. Perhaps it was unfortunate for 16th century Incas that King Phillip II was an especially enthusiastic proponent of the counter-reformation and the Inquisition.