South flank of the Wickenburg Mountains, northeast of the Hassayampa River, Tps. 6 and 7 N., Rs. 3 and 4 W.
Wickenburg and Red Picacho 7 1/2-minute quadrangles.
Wilson, Moore, and Peirce, 1957, Geologic map of Maricopa County, scale 1:375,000.
Jeep trails lead to low hills on north side of U.S. Highway 60-70-89 near San Domingo Wash, 7 miles southeast of Wickenburg, 3 miles northwest of Morristown.
The placers in the San Domingo district are found in San Domingo Wash, its tributaries and adjacent washes, and on mesas between gulches. The placer area is southwest of a low range of hills that includes the prominent San Domingo Peak; the drainage of the area is southwestward to the Hassayampa River.
Many washes are mentioned in the literature as scenes of active placer mining, but the topographic maps of the area locate only San Domingo Wash, which drains through sees. 25 and 26 and 35, T. 7 N., R. 4 W., and sees. 2 and 3, T. 6 N., R. 4 W. (Wickenburg quadrangle) and Little San Domingo Wash (Tps. 6 and 7 N., R. 3 W., Red Picacho quadrangle).
Other washes placered are Old Woman Gulch, Rogers Wash, American Gulch, Spring Gulch, and Sanger Gulch. Old Woman Gulch is described as a southern tributary of San Domingo Wash; two tributaries enter San Domingo Wash from the south in the placer area—one tributary joins San Domingo Wash in sec. 2, T. 6 N., R. 4 W., the other, in sec. 5, T. 7 N., R. 4 W. Rogers Wash, which has been described by reporters in a series of articles (Carter, 1911, 1912; Dinsmore, 1911a; Hafer, 1911), is 2 1/2 miles long and is probably the wash located 1 1/2 miles northwest of the mouth of San Domingo Wash.
The principal placer area in Rogers Wash is probably in sec. 26, T. 7 N., R. 4 W. (Wickenburg quadrangle). The Alibu placer (SE14 sec. 28 T. 7 N., R. 4 W.) is adjacent to the highway midway between this wash and Monarch Wash on the north. "Spring Gulch" is probably "Tub Spring Gulch," a headward tributary to San Domingo Wash (T. 7 N., R. 3 W.). The other two placerbearing washes are not located. The gravels in the Hassayampa River contain gold for a few miles below San Domingo Wash.
The San Domingo district has the largest recorded placer gold production in Maricopa County and produced continuously (although on a small scale) from 1905 to 1951. During the early 1960's gold was recovered as a byproduct of gravel operations and by large-scale operations of a mobile dryland dredge.
It is not known when the placers were discovered, but the district was actively worked during the period 1870-80. It is said that the greatest production occurred during this time, when individual placer miners recovered $15-$ 100 per day. Old Woman Gulch was a large producer in 1875 (one report indicates 1885) , and American Gulch reportedly produced "fortunes" for California miners at the same time.
Between 1910 and 1912, the district was actively prospected by Mr. John Sanger, who started the Lotowana Mining Co. and planned to mine 4,000 acres of placer ground on a large scale. The company concentrated its exploration efforts in Rogers Wash, where the average value of the ground was 68 cents per cubic yard, but where the value of some strips was as high as $1.19 to $1.36 per cubic yard.
A dam built by Mr. Sanger across San Domingo Wash failed because the intended reservoir filled with sand and gravel before operations had finished one season. Actual production by the Lotowana Mining Co. is not known.
Since 1912 the records indicate only small-scale operations in the district until the late 1950's. In 1959 the MacDonald Construction Co. recovered gold from gravels that were sorted according to size. Fine gravel (minus 3/16 in. mesh) contained most of the gold; coarser gravel (plus 3/16 in. to minus 3/4 in.) was sent to a nugget trap part of the time.
During the period 1960-62 a dryland dredge, "Geraldine", owned by United Placers Industries, Inc., worked the gravels in the San Domingo district. The operation of this dredge received considerable attention in mining journals; but production records are confidential, and the success of the operation is not known.
The San Domingo district is predominantly a placer-mining district, and there is very little literature available that describes the gold-bearing veins. The origin of the placer gold is said to be from Precambrian and post-Cambrian veins in the area.
Allen, 1922: Location; source; virtually repeats information described by Carter (1912).
Arizona Engineer and Scientist, 1961: Describes dryland dredge; average gold values of placer deposits; mining techniques; size of gold-bearing gravels.
Carter, 1911: Location; describes Rogers Wash; character of gravels; fineness and shape of gold; accessory minerals; distribution of gold in gravels; placer-mining techniques and development.
1912: Drywashing along the Hassayampa River. Locates Rogers Wash; bedrock geology; distribution of gold in gravels; placermining techniques and development.
Dinsmore, 1911a: Location; placer-mining developments; history of placer mining; early production from placer washes; character of placer gravel; grade of gravel.
Engineering and Mining Journal, 1961: Describes dryland dredge "Geraldine"; mining techniques.
Hafer, 1911: Brief description of placer ground.
Heikes and Yale, 1913: Describes Rogers Wash; virtually repeats articles by Carter; adds no new information.
Jahns, 1952: Describes pediment gravels; no placer description.
Roseveare, 1961: Placer-mining operations during the period 1959— 61; size of gold-bearing gravel fractions.
Wilson, 1961: Location; history; source of gold; size of nuggets; distribution of gold in gravels; gold values in gravels.