674 



UNITED STATES MINERAL RESOURCES 



fornia. These deposits, though locally high grade, 

 are small and appear to be related to more exten- 

 sive vein deposits in the same area. 



Huebnerite occurs in small amounts disseminated 

 through large volumes of the porphyry-molybdenum 

 ore body of the Climax Molybdenum Co. at Climax, 

 Colo. Although the grade of the tungsten is only a 

 few hundredths of 1 percent and thus is far below 

 the economic cutoff for tungsten alone, the hueb- 

 nerite is recovered as a byproduct of the very large 

 scale mining for molybdenum and has become a very 

 significant source of domestic supply; in 1970, Cli- 

 max was second only to Pine Creek, Calif., in United 

 States production of tungsten. The geologic evolu- 

 tion of the Climax stock and the sequence of min- 

 eralization are extremely complex and have been 

 well documented in the literature (Wallace and 

 others, 1968). The composite Climax stock was in- 

 truded into Precambrian schist and gneisses and 

 comprises four separate intrusions, each of which 

 had its own associated hydrothermal event. The first 

 three of these produced large stockwork ore bodies 

 and associated alteration zones that cap and flank 

 each intrusive body. The positioning of these sepa- 

 rate intrusions in the same area has led to much 

 overlapping and juxtaposition of ore zones. Each 

 mineralizing episode, however, produced a generally 

 consistent pattern of ore distribution with a molyb- 

 denum-rich zone overlain by a zone with low molyb- 

 denum but anomalous amounts of huebnerite and 

 pyrite. The upper, currently producing molybdenum 

 ore body is overlapped by one of the tungsten- 

 bearing halos. 



The Climax deposit is the only one of this kind 

 in the United States from which byproduct tungsten 

 is recovered. However, the reported association of 

 tungsten minerals with geologically similar deposits, 

 not only in Colorado but also in New Brunswick, 

 Canada, raises the potential for this type of occur- 

 rence to become an increasingly important source of 

 future supply. 



OTHER MODES OF OCCURRENCE 



Pegmatites containing scheelite or wolframite or 

 both are found in many parts of the world, and in 

 many places are closely associated with tungsten- 

 bearing quartz veins near the contacts of intrusive 

 bodies. For the most part, the deposits are small 

 and because of their irregular and generally pockety 

 nature are difficult to exploit. A relatively insignifi- 

 cant percentage of the world production has come 

 from pegmatites. The only important tungsten- 

 bearing pegmatites in the United States, those at 

 the Oreana mine, Pershing County, Nev., were 



largely mined out in the 1940*s. Other occurrences 

 with very minor production are in the southern 

 Black Hills of South Dakota and at Silver Hill near 

 Spokane, Wash. 



The mushroom-shaped scheelite ore body of the 

 Yellow Pine mine, Idaho, was a replacement of brec- 

 ciated quartz monzonite near a major shear zone 

 (Cooper, 1951). The gangue comprised crushed 

 country rock replaced by fine orthoclase and quartz. 

 Early-formed gold, pyrite, and arsenopyrite were 

 followed by scheelite and subsequently by stibnite 

 with some silver. This ore body, which produced 

 about 826,900 units WO3 during 1941-45, has been 

 mined out. 



The replacement of a bed of sandy dolomite in 

 the northern Black Hills of South Dakota by wolf- 

 ramite accompanied by gold, barite, and a little 

 scheelite and stibnite is apparently unique in the 

 United States (Runner and Hartmann, 1918). 



Several manganese- and iron-oxide deposits of 

 hot-spring origin in the Western United States con- 

 tain significant amounts of tungsten in a form still 

 unidentified but apparently closely associated with 

 the oxide minerals. These deposits, formed at or 

 very near the surface, comprise various mixtures of 

 manganese and iron oxides in surficial alluvial 

 materials, as hot-spring aprons, or as near-surface 

 veins. Only the large deposits at Golconda, Nev., 

 where tungsten-bearing oxides impregnate Pleisto- 

 cene continental fanglomerate, contained enough 

 tungsten to be exploited (Kerr, 1940). 



Anomalous amounts of tungsten have been re- 

 ported from other hot-spring deposits as well as 

 from epithermal manganese-bearing veins in Ne- 

 vada, Oregon, New Mexico, and Bolivia. Many others 

 probably exist, but because of their usual small size 

 and the metallurgical problems they pose, they will 

 probably always represent a very small part of 

 world resources. 



Commercial concentrations of tungsten minerals 

 in stream placers are rare and are generally re- 

 stricted to areas close to abundant coarse-grained 

 source material as in the Atolia-Randsburg district, 

 California. A small amount of fine-grained scheelite 

 was recovered as a coproduct with gold from placers 

 that were dredged for several miles in Henderson 

 Gulch, Mont., downstream from the mineralized 

 stockwork deposit previously described. Small 

 amounts of wolframite have been recovered from 

 eluvial material in the Germania district, Stevens 

 County, Wash. 



Significantly larger amounts of placer tungsten 

 are reported to have been recovered from eluvial 

 and stream placers in the great Chinese tungsten 



