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test , 8 juli 2012
U.S. Geological Survey, Mineral Commodity Summaries, January 2011</ref> with a slight decrease in 2012 to only 50,000 tonnes per year.[1] with a slight decrease in 2012 to only 50,000 tonnes per year.<ref>Niobium (Colombium)
- ↑ Niobium (Colombium)
web.archive.org , 8 juli 2012
U.S. Geological Survey, Mineral Commodity Summaries, January 2011
