Copper was found in the Yerington District very early in history of Nevada, in 1865. A number of copper veins were mined around Yerington. Many of these mines were of a type called skarn, in which hot fluids from a granitic type rock change limestones into ore. Often skarns contain very interesting minerals. In the Yerington area, skarns are found with garnet and epidote. Copper in these mines is found in the mineral chalcopyrite.
The other major ore deposit type in the Yerington District is porphyry copper, just as we have seen in Battle Mountain, in Bingham Canyon, in many Arizona mines, and in Chile. The granite-type rock adjacent to Yerington in the Singatse Range contains scattered pods, veins, and grains of chrysocolla, a blue copper silicate mineral, along with green malachite, purple cuprite, and brassy chalcopyrite.
The early mines followed veins and skarns. Until 1940, the district produced over 17 million dollars, chiefly in copper. However, a very large and important copper mining company, Anaconda, began exploring the granitic rocks next to the town of Yerington. In 1953, Anaconda produced copper at its mill in the town of Weed Heights, adjacent to Yerington. Between 1953 and 1965, Anaconda produced 803,224,674 pounds of copper, worth $255,154,480.
The Yerington pit is played out now, filling with water. But another copper mining company, Arimetco, is operating the MacArthur pit, afew miles north of Yerington. Last year it produced 12,995,000 pounds of copper. The town of Yerington has been a ranching and farming center, as well as a mining town. It never depended entirely on copper mining, and it never became a ghost town.
The pit at the former copper mine has filled with about 40,000 acre-feet of contaminated water as can be seen on great photo here and Google.