Yuma County Arizona Gold Production
The La Paz (Weaver) district, in west-central Yuma County, is 9 miles west of Quartzite and 6 miles east of the Colorado River, along the west side of the Dome Mountains.
Gold has come chiefly from placers, but a small amount has been mined from quartz veins. Indians gave a few nuggets to a trapper in 1862 and guided him and his party to the rich gold-bearing gravels. News of this spread quickly, and several hundred miners rushed to the new area. By 1864, however, the higher grade placers were exhausted. The district was dormant until 1910, when plans were made to mine the gravels by hydraulic methods. These operations were thwarted when the land was included in an Indian reservation. Several later plans for large-scale mining were never carried out (Wilson, 1952, p. 25, 26). Lode deposits, probably discovered at about the same time as the placers, were worked intermittently and yielded about $100,000 worth of gold through about 1933 (Wilson and others, 1934, p. 136).
The placer gold production was estimated at about $2 million (96,800 ounces) in the first 5 years (Browne, 1868, p. 454-455). Total production from placers through 1959 was about 100,000 ounces, and total output from lodes was about 4,000 ounces.
The placers occur along gulches that drain the western slopes of the Dome Rock Mountains. These include the Goodman Arroyo and Arroyo La Paz and their tributaries, among which is Ferrar Gulch which contained the richest and most productive gravels of the district. The gold was recovered entirely by dry washing (Jones, 1916a, p. 49-52).
The rocks in the La Paz district are chiefly Precambrian schist and gneiss which were intruded by granitic rock of probable Mesozoic age (Wilson, 1952, p. 28). The gold occurs in quartz veins in the schist. Some of the veins are parallel to the foliation and others, referred to as gash veins, cut across. Those along the foliation are the larger; the gash veins are too small for exploitation (Jones, 1916a, p. 54-55).
PLOMOSA DISTRICT
The Plomosa district is near the town of Quartzite on La Posa Plain, between the Plomosa Mountains on the east and the Dome Rock Mountains on the west.
This is mainly a placer district; however, gold, copper, and lead have been produced from lode mines. In 1862, prospectors on their way west to the rich La Paz gravels found placers on the east side of the Dome Rock Mountains, at Oro Fino, La Cholla, and Middle Camp. These were worked intermittently until the 1950's, and several unsuccessful attempts were made to mine the gravels on a large scale (Jones, 1916a, p. 52). Gold, copper, and lead veins were exploited after 1900 but their yield was small (Nolan, in Hewett and others, 1936, p. 33). Total gold production of the district through 1959 was about 24,570 ounces: about 19,400 ounces from placers and about 5,000 ounces from lodes.
The northern Plomosa Mountains, in which the auriferous veins occur, are composed of metamorphosed limestone, shale of probable Cretaceous age, and intrusive granite (Wilson and others, 1934, p. 134-135). The veins are along a fault zone in the shale. Gold occurs in fine flakes with hematite.