Location
At the north end of the Tank Mountains near Engesser Pass and at the southeastern foothills of the Tank Mountains, T. 2 S., Rs. 15 and 16 W.; T. 4 S., R. 13 W.
Topographic Maps
Engesser Pass and Palomas Mountains 15-minute quadrangles.
Geologic Map
Wilson, 1960, Geologic map of Yuma County, Arizona, scale 1:375,000.
Access
From Yuma, 59 miles east and north on State Highway 95 to dirt road leading east about 15 miles to dirt road leading about 10 miles north to the Kofa Mountains.
Extent
Placers are in many parts of the Tank Mountains and have been worked on a small scale since the 1870's. The only information I have found on the extent of these deposits is that given by Wilson, who describes two areas of placer concentration—near Engesser Pass and near Puzzles Mountain.
The Engesser placer is at the north end of the Tank Mountains (in the vicinity of the boundary between T. 2 S., R. 15 and 16 W., Engesser Pass quadrangle); the gold was recovered from gravels in the main gulch below the Engesser prospect (sometimes called the Johnnie Prospect) and from gravels in smaller nearby gulches.
The Puzzles area placer is in the southeastern foothills of the Tank Mountains, in the vicinity of a low ridge locally called Puzzles Mountains (NW14 T. 4 S., R. 13 W.; Palomas Mountains quadrangle). The gold was recovered from shallow bench and stream gravels on the pediment near the Puzzles, Golden Harp, Ramey, and Regal prospects and is said to be coarser than the gold recovered near Engesser Pass.
Production History
The placers have apparently been worked intermittently on a very small scale since the 1870's, but because of the relative isolation of the district compared with those on the Gila River, very little information has been published. Wilson suggests that the placers in the Engesser mine area were probably worked earlier and with greater profit than the placers in the Puzzles area.
Burchard describes the 1884 discovery of placers located 50 miles from Castle Dome Landing and 80 miles southeast of Ehrenberg; these deposits were probably found in the Tank Mountains, perhaps in the Engesser placer area. A small production of placer gold was reported from the Engesser area in 1936. The placers in the Puzzles area, which is 5 miles north of the Palomas Mountains, were actively drywashed in the early 1900's and probably produced placer gold attributed to the Palomas Mountains.
Source
The placers in the Tank Mountains were derived from local gold-bearing veins, which are mined at the Engesser, Puzzles, Golden Harp, Ramey, and Regal prospects.
Literature
Burchard, 1884: New placer discovery; location; discoverer named; distribution of gold; production.
1885: Repeats 1884 description; adds information on size and shape of gold; source.
Wilson, 1933: Location; history; source; bedrock geology.
1961: Virtually repeats information in Wilson (1933).
