The earliest miners in what is now Arizona were Native Americans who chiefly mined surface outcrops of salt, clays, hematite, quartz, obsidian, stone, turquoise, and coal.
In the late 1600s, Spanish explorers hunted for metallic deposits with especial interest in gold and silver.
Antonio de Espejo made the first major silver discovery  south of the San Francisco Peaks in May 1583, near what some believe is present-day Jerome, Arizona.
By the late 17th Century, Spanish prospectors had engaged in extensive mining in the mountains bordering the Santa Cruz River and its tributary Sonoita Creek. Rare discoveries of sheets or “planchas” of silver – one sheet reportedly weighted 2700 pounds – fired the imaginations of several generations of miners. (Image to left: Early day miners stand in front of a mine portal near Morenci, AZ)
In 1854, in Ajo, Arizona, the Arizona Mining and Trading Company launched the modern era of hard-rock mining.
A burgeoning mining industry stimulated early growth in the Arizona Territory, and by 1864 nearly 25 percent of the male, non-native populace was prospectors.

By the 1870’s a plethora of hardrock mines were yielding prodigious volumes of copper, lead, zinc, silver and gold ore.  In 1912, the newly christened state of Arizona supported 445 active mines, 72 concentrating facilities, and 11 smelters with a gross value of nearly 67 million dollars — equivalent to1.4 billion dollars in 2006 dollars.
Adapted from:
Arizona Geological Society
Arizona Historical Society