National Mineral-Resource Assessment: The 1996 estimate of undiscovered gold, silver, copper, lead, and zinc remaining in the United States

Mining has occurred in the United States from pre-Revolutionary times. How much of our Nation's total mineral wealth has already been discovered? How much is left? For conventional-type deposits that contain gold, silver, copper, lead, or zinc, about as much is left to be discovered in the conterminous 48 States as has already been discovered.