This district is in northwestern Calaveras County in the vicinity of the old mining town of Paloma. Much of the gold produced in the district has come from the famous Gwin mine, which was operated on a large scale during the 1860s, 1870s, and from 1894 to 1908. The mine, named for U.S. Senator William Gwin, had a total output valued at about $7 million.
The gold-bearing veins are in the same belt of slate of the Mariposa Formation (Upper Jurassic) on which the large Jackson district mines lie, in Amador County to the north (see fig. 12). The quartz veins strike north-northwest and dip steeply to the east. The ore contains free gold, pyrite, and arsenopyrite. Milling orc recovered from the Gwin mine averaged about Y4 ounce gold per ron. The great north orc shoot in this mine had a horizontal stoping length of up to 800 feet and a pitch length of 1500 feet.
Clark, W.B., and lydon, P.A., 1962, Calaveras County, Gwin mine: California Div. Mines and Geology County Report 2, pp. 56-59.
Turner, H.W., 1894, Jackson folio, California: U. S. Geol. Survey Geol. Atlas of the U. S., folio 11, 6 pp.