sentences:  In 1585, Spanish explorers made note of the ore but did not mine it because their government had sent them to find gold and silver, not copper.The area became part of Mexico when Mexico gained its independence from Spain in 1821, and part of the United States by terms of the 1848 Treaty of Guadalupe Hidalgo, which concluded the Mexican–American War.The war's major consequence was the Mexican Cession of the northern territories of Alta California and Santa Fe de Nuevo México to the United States.