Carbonatites of the world, explored deposits of Nb and REE; database and grade and tonnage models

Online link http://pubs.usgs.gov/of/2009/1139/
Description Data on 60 of the 527 known carbonatites in the world, providing reliable quantitative data on ore tonnages and grades of niobium and REE.
Originators Berger, Vladimir I.; Singer, Donald A.; and Orris, Greta J.
Publication U.S. Geological Survey Open-File Report 2009-1139
Metadata Questions and answers