Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 500 | Metric tons of gross weight | NA |
| 2003 | 500 | Metric tons of gross weight | 0.00% |
| 2004 | 500 | Metric tons of gross weight | 0.00% |
| 2005 | 500 | Metric tons of gross weight | 0.00% |
| 2005 | 500 | Metric tons, gross weight | 0.00% |
| 2006 | 500 | Metric tons, gross weight | 0.00% |
| 2006 | 500 | Metric tons of gross weight | 0.00% |
| 2007 | 500 | Metric tons, gross weight | 0.00% |
| 2008 | 500 | Metric tons, gross weight | 0.00% |
| 2009 | 500 | Metric tons, gross weight | 0.00% |
| 2009 | 500 | Metric tons of gross weight | 0.00% |
| 2010 | 550 | Metric tons of gross weight | 10.00% |
| 2011 | 550 | Metric tons of gross weight | 0.00% |
| 2012 | 500 | Metric tons of gross weight | -9.09% |
| 2013 | 500 | Metric tons of gross weight | 0.00% |
