TUNGSTEN 



675 



province and from the extension 6f this province 

 into Indochina. 



A small but anomalous amount of WO3 is pres- 

 ent in the saline brines of Searles Lake (Carpenter 

 and Garrett, 1959) and, to a lesser extent, in Owens 

 Lake, both of vi'hich are a part of the Pleistocene 

 Owens River interior drainage system in eastern 

 California. The drainage area includes the eastern 

 slope of the Sierra Nevada and the tungsten depos- 

 its of the Bishop region — from which much of the 

 tungsten in the brines was probably leached. Nu- 

 merous springs, at least one of which is known to 

 carry anomalous amounts of tungsten today, may 

 also have contributed to the total tungsten that 

 collected in the lakes at the time of the through- 

 going Pleistocene drainage. 



Tungsten in Searles Lake occurs as a solute, 

 probably as a complex ion, in the brines in the 

 amount of about 0.007 percent (70 ppm) WO3. Al- 

 though the amount is low, and no efficient extrac- 

 tion method has yet been designed, these brines must 

 be considered a major resource for future considera- 

 tion, because the large volume of brines contains 

 approximately 8.5 million units WO3 — more than 

 half the known reserves of the United States. 



RESOURCES 



IDENTIFIED AND HYPOTHETICAL RESOURCES 



Reserves of tungsten in the United States are 

 estimated to be nearly 15 million short ton units 

 WO3 in ore containing more than 0.3 percent WO3. 

 This is about 6.5 percent of an estimated world 

 reserve total of 230 million units. Nearly two-thirds 

 of the U.S. reserves occurs as scheelite in tactite 

 deposits located principally in California, Nevada, 

 and Montana. Other tactite occurrences are located 

 in Utah, Arizona, Washington, and Idaho. Most of 

 the remaining one-third of the reserves is found as 

 ferberite, wolframite, and huebnerite in quartz veins 

 in Arizona, Idaho, Colorado, and North Carolina 

 and as huebnerite in the Climax porphyry-molyb- 

 denum deposit of Colorado. 



An illuminating aspect of the resource potential 

 for tungsten in the United States is the fact that 

 since 1955 the total United States reserves have 

 remained stable or have increased significantly — 

 especially in recent years. This has occurred in spite 

 of the very high rate of production in the mid- 

 1950's and the industry's relatively depressed con- 

 dition since then. Presumably this fact reflects new 

 discoveries during periods of active exploration and 

 exploitation as well as significant extension of re- 

 serves in the few major mines that have produced 

 more or less continuously. 



In addition to its reserves, the United States has 

 numerous deposits containing less than 0.3 percent 

 WO3 that may be considered as conditional re- 

 sources. Most of these resources are in tactites and 

 stockworks, and they are estimated to total two 

 to three times the known U.S. reserves. The 8.5 

 million units WO3 in Searles Lake brines is an addi- 

 tional conditional resource. 



An extrapolation of identified resources into the 

 realm of hypothetical ore bodies may reasonably be 

 attempted on the basis of our knowledge of regional 

 distribution, modes of occurrence, and geochemical 

 association. Those parts of the Western United 

 States from which most of our tungsten has been 

 produced include vast areas covered by surficial 

 debris and Tertiary sedimentary or volcanic rocks 

 that undoubtedly conceal deposits at least equal in 

 volume to, if not greatly exceeding, known deposits. 

 Also, the proved association of important amounts 

 of tungsten with molybdenum in porphyry-molyb- 

 denum deposits presages the discovery of others of 

 this type, especially in Colorado. No real measure 

 of tungsten recovery irom this source in other parts 

 of the country is yet available, but because of the 

 tremendously large molybdenum resources esti- 

 mated for deposits of this kind, the potential for 

 tungsten byproduct recovery is proportionately 

 large. 



More than 90 percent of the world's known tung- 

 sten reserves are outside the United States, with 

 60 percent in southeastern China. Table 146 sum- 

 marizes the general reserve estimates and geologic 

 characteristics of the major tungsten-producing 

 countries of the world. Reserve figures are estimates 

 only, and those for Communist countries, where in- 

 formation is outdated, inadequate, and difficult to 

 evaluate, are far less reliable than those for the 

 free world. 



SPECULATIVE RESOURCES 



The worldwide pattern of tungsten distribution, 

 combined with the known geologic conditions re- 

 lated to its localization, leads to broad speculation 

 of ultimate potential which can reasonably be ex- 

 tended an order of magnitude beyond the identified 

 and hypothetical world resources. 



The localization of many of the major tungsten 

 districts of the world in a broad circum-Pacific belt 

 extending from South America through the United 

 States, Canada, Alaska, and down the eastern coast 

 of Asia into Australia and Tasmania, marks this 

 zone as one in which other deposits or districts may 

 very likely be found. The discovery and extensive 

 production from contact-metamorphic deposits in 



