Niobium and tantalum: indispensable twins

Online link http://pubs.usgs.gov/fs/2014/3054/
Description Explains how we use these chemical elements, where they come from, and characteristics of the global supply and demand for them.
Originators Schulz, Klaus J. and Papp, John F.
Publication U.S. Geological Survey Fact Sheet 2014-3054

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