The majority of that wealth went into developing Spain's military capabilities. In the 16th and 17th centuries, Spain was involved in many wars during the Protestant Reformation of Europe, defending the Catholic Church. Notably, these wars included the wars in German States, the French Wars of Religion, the Eighty Years War in the Netherlands, and the Thirty Years War. Spain also fought vigorously for control of southern Italy and to repel the Ottoman advances in Southeast Europe. A minority went into developing infrastructure in Spain, making large palaces, impressive boulevards, and better postal roads.
for the gold of the Americas
There was some gold and silver in Spain, but what made Spain rich in the 16th and 17th centuries was the gold and silver taken from Spanish possessions in the Americas.
Spain became wealthy from the gold and silver found in the Americas, particularly in regions like Mexico, Peru, and Bolivia. The influx of precious metals from these sources significantly boosted Spain's economy during the 16th and 17th centuries.
Spain's economy didn't benefit from the gold and silver from the Americas because although it did make Spain wealthy for some time, it caused the value of their money to drop and as the demand of physical elements increased, so did prices (inflation) causing Spain's economy to fail
The availability of advanced shipbuilding technology, funding from the Spanish monarchy, and the hope of finding valuable resources like gold and silver all significantly increased Spain's exploration of the Americas.
Mining gold and silver was most important in colonies that belonged to Spain, as they sought to establish a strong economy based on extracting and exporting precious metals from their territories in the Americas.
Primarily to convert all the heathen natives to Christianity, and remove as much gold, silver and other wealth back to Spain.
That was a driving force to their take over of the Americas. Spain became rather rich with the gold and silver that was brought back from the are.
Spain hoped to spread Christianity through missions and convert indigenous populations to Catholicism. They also aimed to exploit the wealth of the Americas by mining precious metals like gold and silver.
Spain was hovering on the edge of financial ruin. Through the explorations in the Americas, they found mines and relics of gold, silver and other important natural resources. These items were taken back to Spain to support their country and continued exploration with little regard for those who were stolen from.
to look for gold
Initially Europeans explored the Americas in search of gold, silver and precious stones.