Location
West flank of the Dome Rock Mountains, Tps. 3 and 4 N., Rs. 21 and 22 W.
Topographic Maps
Dome Rock Mountains 15-minute quadrangle; La Paz Mountain 7 1/2-minute quadrangle.
Geologic Maps
Jones, 1915, Map showing geology of southern part of Colorado River Indian Reservation and location of placers near Quartzsite, Arizona (pi. 4), scale approximately 3 miles = 1 in.
Wilson, 1960, Geologic map of Yuma County, Arizona, scale 1:375,000.
Access
From Yuma, 84 miles north on State Highway 95 to Quartzsite, about 10 miles west on U.S. Highway 60-70 to placers, which are adjacent to the highway and in nearby gullies and washes.
Extent
Placers in the La Paz district are found in Goodman Arroyo and Arroyo La Paz, major west-trending drainages, and in Ferrar, Garcia, and Ravenna Gulches, tributaries to the major drainages. Placers were worked as far west as the outskirts of the town of Ehrenberg (sees. 15 and 16, T. 3 N., R. 22 W.).
The gold-bearing gravels range in thickness from a few feet on the mountain slopes to an unknown depth in Arroyo, La Paz, and Gonzales Wash (the wash through which U.S. Highway 60-70 is built); gold is distributed throughout the gravels, but the richest parts were found near bedrock. Ferrar Gulch (sees. 25 and 36, T. 4 N., R. 21 W.) reportedly contained the richest gravels in the area, and it was from this gulch that Juan Ferrar recovered a nugget weighing more than 47 ounces.
Production History
The placers in the La Paz district were discovered by Captain Pauline Weaver in January 1862, when he panned a small amount of gold from a gulch called El Arollo de la Tenaja in the Dome Rock Mountains. Immediately thereafter, Weaver returned to Yuma, told about his discovery, and on his return to the mountains was joined and followed by other prospecting parties (Browne, 1868, p. 454).
According to Browne, this advance party soon found good prospects (one man, Jose Redondo, recovered a nugget weighing more than 2 oz in a place less than a mile south of Weaver's camp) and returned to Laguna for supplies. The real rush to the new placer soon followed. About $1 million in placer gold was recovered from the placers the first year and another $1 million by 1864, when the placers were worked out.
Since that time, the La Paz district has been at times part of the Colorado River Indian Reservation, and in consequence, small-scale placermining activity declined and large-scale placer-mining plans were interrupted. During the 20th century, while many large-scale operations were active in the Plomosa district to the east, the La Paz placers were worked only by individuals.
The La Paz placers are famous for the large nuggets recovered, although most of the gold occurred as pieces ranging in weight from 0.0025 to 0.5 ounce. Browne (1868, p. 454) describes large nuggets from the gravels, some weighing 26, 27, and 47 ounces, that were free of all foreign material, even quartz, and thought it possible that many larger nuggets were recovered but not shown for various practical or superstitious reasons.
The largest nugget recovered from the La Paz placers was valued at about $1,150 (about 65 oz) and assayed 870 fine (Heikes and Yale, 1913, p. 259; Jones, 1915,p. 50); Jones attributes the recovery of this nugget to Juan Ferrar. As late as the 1930's, a nugget valued at $900 (about 45 oz) was recovered by a prospector (MacHunter and Henderson, 1958); most of the large nuggets were found years earlier; later workers found only smaller particles.
Source
The discovery of the La Paz placers led to intensive prospecting for large gold-bearing veins, but major lode mines have not been developed. The gold in the placers is attributed to erosion of the many gold-bearing veins distributed through the metamorphic rocks in the area. Some of these veins, such as the Goodman vein, which trends northwest-southeast across the north end of Ferrar Gulch and is exposed in Gonzales Wash, have been mined in the past.
Jones (1915, p. 54) states that the decomposition of these veins has produced the placer gold, as the largest areas of placer gravels are found along the more persistent gold-quartz veins.
Literature
Allen, 1922: Location; quotes description of Jones (1915); placermining operations; gold values per cubic yard; production.
Bancroft, 1911: Quotes Browne (1868).
Browne, 1868: Gives a complete history of discovery and early activity in placers in the La Paz district on p. 454-455.
Heikes and Yale, 1913: Location; thickness of gravels; gold values per cubic yard; size of nuggets; placer-mining operations.
Hinton, 1878: History of early placer mining; later placer discoveries.
Jones, 1915: Detailed description of La Paz placers; mining methods; depth and extent of workings; amount and type of gold removed. Relations to local geology discussed.
Koschmann and Bergendahl, 1968: History; production.
MacHunter and Henderson, 1958: Popular account of discovery and subsequent development of La Paz diggings. Photographs of area included.
Randolph, 1901: Size of nuggets recovered.
Raymond, 1872: Geology; origin of the placers.
1874: Production information for 1873.
Trippel, 1889: Production statistics for 1888.
Wilson, 1961: History; location; placer-mining techniques; source; quotes descriptions of earlier studies.
