| 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 |