NIOBIUM (COLUMBIUM) AND TANTALUM 



453 



out special means because of their insolubility in 

 most solutions and their refractory nature. Quali- 

 tative and quantitative chemical determinative pro- 

 cedures have been developed for niobium and have 

 been used in the field. Such chemical procedures 

 have not been satisfactorily developed to conven- 

 iently detect tantalum. The capacity to analyze large 

 numbers of samples at the site has been demon- 

 strated by Grimes and Marranzino (1968), utilizing 

 truck-mounted spectrographic equipment, and this 

 method has been effective for rapid determination 

 of niobium. Similar rapid analyses for both niobium 

 and tantalum can be accomplished in the laboratory 

 by X-ray fluorescence spectroscopy. 



PROBLEMS FOR RESEARCH 



One of the basic problems relating to niobium and 

 tantalum is the lack of domestic selfsufficiency in 

 resources of these elements in the United States. 

 The United States is the world's largest single con- 

 sumer, but these commodities are almost entirely 

 imported. On a worldwide basis, supplies of niobium 

 are more than adequate for projected needs to the 

 year 2000 (Griffith, 1970) with chief sources in 

 Brazil, Canada, and the African continent. 



Tantalum resources also are very limited in the 

 United States, and ores are wholly imported from 

 Brazil, Canada, and certain African countries. Even 

 on a worldwide basis, the known resources of tanta- 

 lum are not large, and this fact has served to limit 

 industrial use of the metal and to discourage re- 

 search on new applications. Pegmatites and placers 

 are the only known commercial sources of this metal, 

 and low-grade large-tonnage commercial deposits 

 have yet to be discovered. 



Geologic research is needed to explore the possi- 

 bilities of the existence of additional types of tanta- 

 lum deposits. Such research has been hampered in 

 the past by the lack of accurate abundance and ana- 

 lytical data on tantalum that in turn is a result of 

 the lack of availability of sufficiently sensitive 

 analytical techniques. Only neutron-activation analy- 

 sis and elaborate chemical analysis currently are 

 capable of detecting tantalum at the low values at 

 which it is present in ordinary rocks. Research in 

 new analytical techniques should receive first prior- 

 ity in any research effort directed toward discovery 

 of additional resources of tantalum. 



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