TUNGSTEN 



669 



1910 1920 1930 1940 1950 1960 



Figure 73. — United States production and price of tungsten, 1900-1971 



chemistry of tungsten will emerge. The following 

 information is based primarily on recent compilations 

 of the geochemistry of tungsten by Krauskopf 

 (1970) andBarabanov (1971). 



Tungsten (W) is one of the rarer elements in the 

 earth's crust. The average crustal abundance of 

 tungsten has been estimated at 1-1.3 ppm (parts per 

 million) . Of all igneous rocks, those of granitic affini- 

 ties contain the most tungsten (average 1.5 ppm). 

 Mafic rocks have a somewhat lower range of 0.5-1.0 

 ppm and ultramafic rocks the lowest (0.1-0.8 ppm) 

 (Krauskopf, 1970). Sedimentary rocks have an aver- 

 age tungsten content estimated at 1-2 ppm, the 

 amount in clastic sediments generally being higher 

 than that in carbonate rocks. The few data for meta- 

 morphic rocks are too fragmentary to substantiate 

 any general conclusions. 



Meager data suggest that the content of tungsten 

 in natural waters is extremely low. Such low values 

 are compatible with the general insolubility of tung- 

 sten minerals as well as with the strong tendency for 

 any dissolved tungsten to be adsorbed on iron and 

 manganese oxides. The average tungsten content 

 of sea water is probably near 0.0001 ppb (parts per 

 billion) . Lakes and streams probably contain much 

 less than 1 ppb. In acid mine waters associated with 

 tungsten ore deposits, values are as much as 100 ppb 

 tungsten. Exceptionally high values of 40-64 ppm 

 tungsten are reported for the brines of Searles Lake, 

 Calif. In hot spring waters, tungsten content may 

 reach a few hundred parts per billion. 



In general, the content of tungsten in common 

 rock-forming minerals is low. Quartz and feldspar 

 generally have less than 2 ppm, and mica, the rich- 



