Tungsten deposits of Cochise, Pima, and Santa Cruz Counties, Ariz.
Tucson, AZ: U.S. Department of the Interior, Bureau of Mines, RI 5650, 1960 Jan; :1-132
This paper is one of a Federal Bureau of Mines series covering the mineral resources of the Nation. It briefly describes most of the tungsten deposits in Cochise, Pima, and Santa Cruz Counties, Ariz. Most of the descriptions are from field examinations by the two senior writers, prior to July 1957. Wolframite first was identified in Arizona in 1896 by W. P. Blake, Territorial Geologist. Tungsten mining began about 1900 in the Little Dragoon deposits of Cochise County, and about 1901 in Las Guijas district of Pima County. The price history of tungsten is an erratic one; consequently, production has been erratic. Prices rise during wars and periods of national preparedness. Production of tungsten ore was stimulated greatly by a Government purchasing program, announced on May 10, 1951, wherein the Government agree to purchase standard-grade tungsten concentrates a t $63 per short ton unit for 5 years or until 1,468,750 units were purchased. This was later increased to 3,000,000 units, and after this amount had been purchased in June 1956, the purchase of an additional 1,500,000 units was authorized. Government purchase, however, was suspended in December 1956 before completion of this latter program, and the price of tungsten concentrates declined sharply. The price had dropped to $15 per short ton unit, duty extra, by the last part of July 1957. The word "ore" as used in this manuscript does not differentiate between submarginal tungsten-bearing material and ore that could be mined at a profit. A look at the price history will show why it is difficult to classify tungsten-mineral-bearing material. Mining activities were being carried on at only four of the properties visited during the course of this investigation. The majority of the properties contained small, sporadically mineralized, discontinuous ore deposits. However, in two localities, the Chiricahua-Dos Cabezas area of Cochise County, and the Baboquivari area of Pima County, further prospecting and testing might disclose low-grade deposits of sufficient extent to warrant small, open-pit operations during periods of high tungsten price. Virtually all of the deposits are in mountainous country, and since most of them are small, transportation and mining costs are proportionately high. An effort has been made to determine the position of the various deposits by section, township, and range, and to give accurate road directions to each property from a prominent landmark. All available maps have been used to make these determinations, but in unsurveyed areas it has been necessary to make approximate projections of subdivisions. The township and range numbers refer to the Gila and Salt River base and meridian. Numerous rock samples were taken in the field for laboratory identification. When a sample is discussed in the text and followed by a sample number in parentheses, the detailed petrographic description can be found by referring to that number in the Appendix. The Appendix also contains a log of all assays made during the course of the investigation.
Tucson, AZ: U.S. Department of the Interior, Bureau of Mines, RI 5650