The Bureau of Mines is engaged in a program to determine the availability of land for mineral exploration and development in Alaska. Researchers are comparing land availability, based on ownership and federal and state laws and policies, to the distribution of known mineral deposits and terranes. Six regional studies, consisting of extensive data compilation and analysis using mapping techniques, will cover the state. This study encompassed 54.6 million acres in north-central Alaska. Based on the data collected, the researchers divided the land in the study area into 3 availability categories and 15 subcategories. In July of 1985, 18.8 million acres of the study area were available for mineral exploration and development, 6.1 million acres were available with restrictions, and 29.7 million acres were unavailable. Much of the land that is currently classified as unavailable is likely to be reclassified; however, more than half of the unavailable land is federal land considered to be permanently unavailable to mining. About 21.7 million acres in the study area are underlain by mineral terranes (assemblages of related rocks likely to contain mineral deposits with a similar genesis). Of this total, more than 5.7 million acres are available to mineral entry, 2.1 million acres are available with restrictions, and 13.9 million acres are unavailable.