La Cholla placers (Chappo placers; Arizona Drift Mine), La Cholla District, Dome Rock Mts, La Paz Co., Arizona, USA
|Latitude & Longitude (WGS84):||33° 37' 8'' North , 114° 17' 39'' West|
|Latitude & Longitude (decimal):||33.61889,-114.29417|
|Other regions containing this locality:||Sonoran Desert, North America|
‡Ref.: Heikes, V.C. (1913) Arizona, in Precious and semiprecious metals in the western states in 1912 (mine production), in Mineral resources of the United States, calendar year 1912, Part I - Metals: U.S. Geological Survey (Washington, D.C., Government Printing Office), p. 536-568.
Jones, E.L., Jr. (1916b) Gold deposits near Quartzsite, Arizona, in Contributions to economic geology, 1915, Part I: Metals and nonmetals except fuels: U.S. Geological Survey Bulletin 620: 53.
Wilson, E.D. (1927), Arizona gold placers, 2nd. ed. (revised), University of Arizona Bull. 124: 20.
Arizona Bureau of Mines Bull. 135 (1933), Arizona Gold placers & placering: 29-30.
Berger, H.W. (1932) Saving gold in cemented gravels: Mining Journal: 16(14): 7, 28.
Gardner, E.D., and Johnson, C.H. (1934) Placer mining in the western United States, pt. 1; general information, hand-shoveling, and ground-sluicing: U.S. Bureau of Mines Information Circular I.C. 6786, 75 p.
Elsing, M.J. and Heineman, E.S. (1936) Arizona Metal Production, Arizona Bureau of Mines Bulletin 140: 104.
Butler, G.M. (1937) Arizona Gold Placers and Placering. Arizona Bureau of Mines Bull. 142: 29.
Mining Journal (1939): Vol. 22(23): 19.
Wilson, E.D. (1952), Arizona gold placers and placering (Fifth edition revised): Arizona Bureau of Mines Bull. 160: 29.
Wilson, E.D. (1961) Gold Placers and Placering in Arizona. Arizona Bureau of Mines Bull. 168 (revised 1978): 29-30.
Johnson, M.G. (1972), Placer gold deposits of Arizona, USGS Bull. 1355: 28.
Keith, Stanton B. (1978) State of Arizona Bureau of Geology and Mineral Technology, Geological Survey Branch Bull. 192, Index of Mining Properties in Yuma County, Arizona: 157 (Table 4).
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10102574, MRDS ID #M004385; and, Dep. ID #10258967, MAS ID #0040120307.
A small former surface and underground Au-Ag placer mining area some 4 or 5 miles long and of irregular width, located in T.3N., R.20W., eastern foot of the Dome Rock Mountains, 5 miles W of Quartzsite. Owned at times, or in part, by Grossman; Helcion Mines, Inc.; La Posa Development Co.; and, McMillan & Hendrix.
Mineralization is fine to moderately coarse-grained gold, alloyed with silver, in unsorted aggregate of sub-angular to slightly rounded fragments of slate, schist, and quartzite, more or less firmly cemented with calcium carbonate or siliceous cement, resting on a gently East-sloping pediment cut on tilted slate or schist. The best gold values are along channels at bedrock. The gold is particularly concentrated in the vicinity of reefs and undulations on the bedrock surface, or where boulders are present and is derived from numerous, irregular, small, auriferous quartz veins and stringers in Mesozoic metamorphics. Some gold is erratically distributed throughout the gravels. Black sand is abundant only in the shallower diggings.
Workings are mostly dry placer operations on bench gravels, and shallow underground workings from shafts with drifts on old channels on bedrock. Total estimated production from 1860 to recent times (circa 1978) would amount to some 9,500 oz. gold with 900 oz. silver, but accurate production figures are lacking.
2 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Holocene - Gelasian|
0 - 2.588 Ma
|Quaternary surficial deposits, undivided|
Age: Pleistocene (0 - 2.588 Ma)
Description: Unconsolidated to strongly consolidated alluvial and eolian deposits. This unit includes: coarse, poorly sorted alluvial fan and terrace deposits on middle and upper piedmonts and along large drainages; sand, silt and clay on alluvial plains and playas; and wind-blown sand deposits. (0-2 Ma)
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.