The Spanish preferred to enslave them and make them do the mining... At least until they were worked to death that is...
The real Spanish rulers of the time were not the kings who had not been born with excessive genetic defects or had not been poisoned, but their confessors. The policy of the American colonies was decided in the sinister Casa de Contratación in Seville with the sole purpose of extracting the maximum volume of gold and silver. The pettiness and avarice of this institution went so far as to require the captains of the galleons to acquire provisions in Seville for the outward and return journey.
en.wikipedia.org
The salary of a navigator pilot was lower than that of a constable, which explains why British corsair ships knew the navigation routes of the fleet of the Indies.
When the galleons unloaded their cargo, the officials quickly appropriated the metal and threw away everything else: geophysical investigations, seeds, official reports, requests for materials, weapons, naval supplies, navigation equipment, dictionaries of local dialects, examples of indigenous art...
I know of a case of a researcher who sent packages of medicinal herbs, including significant quantities of quinine, for years without getting any response.
He was imprisoned "for embezzlement" upon returning to Spain.
The saddest part of this story is that we Spaniards contributed the ships and the blood and the Genoese and Austrian bankers kept the money to pay off the enormous debts contracted by our foolish rulers.