How might the history of South America and Mexico have been different if the Spanish had not discovered gold and silver there

The history of South America and Mexico might have been different if the Spanish had not discovered gold and silver there because they might not have had strong reasons for further exploration and colonization. Although there were also other benefits beyond gold and silver which served as reasons for colonization it was the discovery of these valuable resources that served as one of the strongest forces for further exploration and colonization.