New definitions for such crucial terms as ‘reserves’ and ‘resources’ in minerals have been jointly adopted by the U.S. Bureau of Mines and the U.S. Geological Survey. The new definitions are more accurate than those they supersede in describing the estimated production potential of mineral deposits, including fuels.

Because the Bureau of Mines and the USGS both collect important information about minerals, a common terminology is essential to evaluate the data for government planning. The classification system agreed upon is based on two key criteria: the extent of geological knowledge about the resource and the economic feasibility of its recovery. The new definitions are listed below.