Tungsten deposits of Yuma, Maricopa, Pinal, and Graham Counties, Ariz.
Tucson, AZ: U.S. Department of the Interior, Bureau of Mines, RI 5516, 1959 Feb; :1-68
This is one of a series of reports covering the mineral resources of the Nation. It describes briefly most of the known tungsten deposits in Yuma, Maricopa, Pinal, and Graham Counties, Ariz. Most of those described were examined by the author. An effort was made to determine the position of the various deposits by section, township, and range and to give accurate road direction to each property from a prominent landmark. All available maps have been used in making these determinations, but in unsurveyed areas it was necessary to make approximate projections of subdivisions. The township and range numbers refer to the Gila and Salt River base and meridian. Work was-being done on only one property visited during the course of this investigation. Only necessary annual assessment work had been done on the majority of the properties during the past 2 years (July 1956-June 1958). Production figures are given for each deposit, where known, and for each county. Reserve estimates were made for the individual counties. All elevations are approximate, having been obtained by aneroid barometer. The occurrence of tungsten minerals is sporadic and discontinuous; hence, samples taken by conventional methods, other than bulk mining, are usually unreliable. The appendix contains a log of all assays made during this investigation. Most of the deposits examined contained shallow surface workings only. At virtually all of them the commercial tungsten ores had been removed as they were found, leaving only marginal and low-grade material exposed. Development workings were found in only three areas, and they were not extensive. The search for new occurrences of tungsten minerals was greatly stimulated in this area by the Government purchasing program announced May 10, 1951, wherein the Government agreed to purchase Standard-grade tungsten concentrates at $63 per short-ton unit. The program, with slight modifications, lasted until December 1956. An investigation was made and a report written on all known tungsten occurrences in Arizona in 1941. Yuma County had 1 known tungsten occurrence in 1941, compared with the 26 described in this paper. On 19 of these properties tungsten minerals were discovered after May 1951. Wilson described only one Maricopa County deposit compared with six described in this paper, five of which were discovered after May 1951. All tungsten occurrences in Pinal County were discovered before May 1951. Field work for this report was done from January to June 1958.
Tucson, AZ: U.S. Department of the Interior, Bureau of Mines, RI 5516