Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2004 | 731 | Metric tons, gross weight | NA |
| 2005 | 958 | Metric tons, gross weight | 31.05% |
| 2006 | 958 | Metric tons, gross weight | 0.00% |
| 2007 | 1173 | Metric tons, gross weight | 22.44% |
| 2008 | 834 | Metric tons, gross weight | -28.90% |
| 2009 | 303 | Metric tons, gross weight | -63.67% |
| 2010 | 249 | Metric tons, gross weight | -17.82% |
| 2011 | 290 | Metric tons, gross weight | 16.47% |
| 2012 | 250 | Metric tons, gross weight | -13.79% |
