This report summarizes the results of the 1998 National Mineral Resource Assessment that estimated the gold, silver, copper, lead, and zinc in undiscovered deposits in the United States. This project also estimated the identified resources and past production of these five metals. Assessment results include the following: It is estimated that 18,000 metric tons (t) of gold, 460,000 t of silver, 290,000 kilotons (kt) of copper, 85,000 kt of lead, and 210,000 kt of zinc are in undiscovered deposits minable with existing technology. In addition, it is estimated that 15,000 t of gold, 160,000 t of silver, 260,000 kt of copper, 51,000 kt of lead, and 55,000 kt of zinc remain in identified resources. Past production from the largest identified resources of gold, silver, copper, lead, and zinc is estimated to be 12,000 t of gold, 170,000 t of silver, 91,000 kt of copper, 41,000 kt of lead, and 44,000 kt of zinc. These deposits account for about 99 percent of cumulative domestic production in the United States."