John L. Sznopek Lorie A. Wagner Daniel E. Sullivan 2000 Price indexes developed by the U.S. Geological Survey (USGS) indicate that the long-term constant dollar price of key U.S. mineral raw materials declined over the last century, even though the need for mineral raw materials increased during the same period. Technologies and reduced production costs have allowed mineral production to remain profitable, while lower priced mineral products from domestic and foreign sources helped fuel growth in other sectors of the economy. application/pdf 10.3133/ofr00389 en U.S. Geological Survey, 20th century U.S. mineral prices decline in constant dollars reports