668 



UNITED STATES MINERAL RESOURCES 



its alloys — extreme hardness, the ability to retain 

 hardness and strength at elevated temperatures, high 

 tensile strength, adequate electrical conductivity, and 

 high wear resistance. The basic forms in which tung- 

 sten is consumed are, in approximate percentages, as 

 follows: tungsten carbide, 45; alloy steels, 25; non- 

 ferrous alloys, 11 ; tungsten and tungsten-base alloys, 

 18 ; chemicals and others, 1 to 2. These various tung- 

 sten materials have important and in some cases 

 very specific application in the production of metal- 

 working machinery, tool steel, construction and min- 

 ing machinery, drill bits, turbines, rocket nozzles, 

 structural material in nuclear and space applications, 

 transportation equipment (including tire studs), 

 electrical equipment, lamp filaments, high-tempera- 

 ture thennocouples, inorganic chemicals for use in 

 dyes, inks, glass, and luminous pigments, and other 

 minor items. More detailed information is given by 

 Grifiith (1970). 



Tungsten, because of its properties, has many uses 

 that are basic to a modern, rapidly diversifying tech- 

 nology; consequently, the metal will continue to be 

 an increasingly important, if not critical, commodity 

 of worldwide importance. Accelerated industrial ex- 

 pansion and new applications predicate an increasing 

 domestic demand for tungsten, which can be met 

 only by discovery of new deposits, by the processing 

 of lower-grade source materials at higher cost, by 

 increased imports from abroad, or by the recycling 

 of tungsten from scrap. An unsatisfactory alterna- 

 tive to an adequate supply is substitution of other 

 metals for tungsten in some end-use applications. 

 Molybdenum is substituted for tungsten in tool steels 

 and high-temperature nonferrous alloys even though 

 these products have a lower melting point, lower 

 hardness at red heat, and a tendency to decarburize. 

 Titanium carbide combined with molybdenum, nickel, 

 or cobalt has gained acceptance in cutting tools; 

 other materials such as aluminum oxides and indus- 

 trial diamonds can be substituted in certain applica- 

 tions. In many lesser uses such as filaments for 

 electric lamps no adequate substitutes are now 

 available. 



U.S. production of tungsten ore has varied widely, 

 and although production peaks have occasionally ex- 

 ceeded consumption lows, the country has, on the 

 average over the past 20 years, produced only about 

 75 percent of its demand. As a result, the United 

 States is a net importer of concentrates, mostly from 

 Canada, Australia, Bolivia, Peru, Portugal, and South 

 Korea. Of the known and estimated world reserves 

 approximating 220 million units Wd (one unit 

 equals 1 percent per ton, or 20 pounds WOs contain- 

 ing 15.862 pounds tungsten metal), about 80 percent 



is estimated to be in Communist countries — 60 per- 

 cent in southeastern China and 20 percent in North 

 Korea and the U.S.S.R. The impact of the Chinese 

 reserves and potential production is the major un- 

 known factor in predicting worldwide tungsten 

 markets. 



EXPLOITATION 



Tungsten mining in the United States began on a 

 very small scale in 1898 with production from peg- 

 matites in Connecticut and South Dakota and from 

 quartz veins in Arizona. The history of production 

 from 1900 to the present has seen wide fluctuations, 

 with short periods of high productivity stimulated 

 by high prices during periods of national emergen- 

 cies or special Government production incentive pro- 

 grams, followed by drastic cutbacks to lower levels. 

 Figure 73 shows curves of production and unit price 

 for the period 1900-1971. The three peaks on the 

 production curve represent the effects of World Wars 

 I and II and of the Government stockpile purchase 

 program during the Korean War. Since 1960, annual 

 production has fluctuated only moderately, and since 

 1965, it has been stabilized in the range of 400 

 thousand to 500 thousand units, largely as the result 

 of the U.S. policy to sell tungsten from Government 

 stockpiles at a fixed price. 



The relation of the price to production (fig. 73) is 

 revealing as to future domestic supplies. Three times 

 in the past 60 years, critical demands for tungsten 

 have been met by domestic production, which sug- 

 gests that the Nation has a relatively high tungsten 

 potential. This is not a low-cost potential, however, 

 when compared to other producing areas in the 

 world, nor is it an indefinite potential ; but under a 

 price incentive, tungsten can be produced in quantity. 

 A U.S. Bureau of Mines tungsten-availability report 

 (Larson and others, 1971) documents this situation. 



The production of tungsten as a coproduct or by- 

 product in various mining operations is discussed 

 later in this chapter. Such sources of supply will 

 likely increase with the continued exploitation of 

 large-volume, low-grade ore bodies. 



GEOLOGIC ENVIRONMENT 



GEOCHEMISTRY 



There is a paucity of data for many aspects of the 

 geochemical behavior of tungsten, and many of the 

 older data (pre-1946) are probably in error because 

 of an earlier lack of methods to analyze accurately 

 for small amounts of tungsten in common rocks and 

 minerals. Only in recent years have these problems 

 been largely overcome, and data are becoming avail- 

 able from which a better understanding of the geo- 



