Mining

The Magma Copper Mine AC system designed by the Carrier Corporation was the first underground mechanical air conditioning system in North America. The initial installation of refrigerated cooling equipment in the Magma Mine at Superior, Arizona was necessary due to the increase in temperature lower into the mine. Below the 2000-foot level, the increase in rock temperature is approximately 1½ degrees F. per 100 feet of depth. The rock temperature on the 2000-foot level is 109°. 

The first authenticated discovery of gold in the U.S. occurred on the Cabarrus County farm of John Reed in 1799, sparking the nation's first gold rush. During its peak years, more than a million dollars of gold was recovered a year, making North Carolina a leader in gold production until 1848. This mill, built by the Mecklenburg Iron Works of Charlotte, North Carolina, is original except for the timber work. Two groups of five 750-pound stamps with 5- to 7-inch lift, rose and fell thirty-five times a minute to yield a finely crushed ore.