What did the Spanish find in North America?

When the Spanish arrived in the Island of Cozumel in Quintana Roo, Mexico in 1519, they were exposed to many new foods, minerals, and an entirely different culture that was presented by the indigenous natives called the Aztecs. However, the element that the Spanish found in North America that caused the fall of Tenochtitlan leading to the conquest of all of Mesoamerica, and a virtual genocide of its people was GOLD.