From the US Bureau of Mines map publication, "Availability of Federally Owned Minerals for Exploration and Development in the Western United States". The Bureau of Mines inventoried Federal mineral land in Wyoming and assessed the availability of this land for mineral exploration and development as affected by legal status and agency management practices. To illustrate the impact that various Federal land use decisions have on the mineral industry, the USBM also identified and ranked known mineral deposit areas (KMDAs)-i.e., areas having past or present mineral production and /or known mineral resources- and compared these areas spatially with availability of Federal mineral lands. Most Federal minerals, except those specifically available through lease or sale, are available by location under the General Mining Law of 1872. Locatable minerals are characterized by relatively high unit value and rare, localized minable occurrence.