The Spanish were overwhelmingly interested in two things during their colonization of the New World: the extraction of New World silver for trade in the European market, and the conversion of the indigenous population to Catholicism. Thus, their behavior, and the methods they used to deal with indigenous populations, was always suited to fulfill either their goal of trade or religious conversion.
The Spanish mining town of Potosi in present-day Bolivia is one of the most famous sites of colonization and New-World mineral wealth. In the middle of the sixteenth-century, Spanish conquistadors and explorers forced the indigenous inhabitants of the region to work in the Spanish silver mines under extreme hardship and unsafe conditions. Work of this kind posed the obvious risks associated with mining, including over-exhaustion, the possibility of a mine explosion or collapse, and the constant inhalation of dust. However, the extensiveness of silver extraction also polluted what little water was available to the inhabitants. Mining processes like the extraction of silver from silver ore redirected the rest. The indigenous laborers were exploited very thoroughly for the sake of Spanish silver lust.
On the spiritual end, the Spanish colonizers were committed to eradicating all New World "pagan" religiosity and turning their new territories into havens of the Catholic faith. Part of their efforts to do so manifested in the famous stories of the torture and execution of indigenous priests who refused to convert to Christianity. It was these abuses against the local population that Bartolome de las Casas so strongly excoriated in his work, A Short Account of the Destruction of the Indies. But Spanish religious efforts also had the effect of integrating large portions of the indigenous population into the Spanish social realm. The encomienda system, for example, encouraged local Spanish warlords to convert as many indigenous souls as possible. By doing so, they could be incorporated into large tracts of land that would then be awarded by the Spanish crown to individual conquerors. These practices, again, destroyed indigenous cultures and ways of life.