The results of this study, conducted under Contract No. So122059, provide a comprehensive up-to-date summary of the large-scale noncoal mining industry. The report identifies problem areas requiring research, identifies potential innovations to improve technology, and provides a basis for anticipating future needs of the industry. It contains statistics on underground mining methods and includes information on the equipment and systems used and on costs and productivity. The report represents the views of nearly one-half of the large underground mine operators in the United States regarding the technology and research needs of their industry. The report describes current practices for various mining methods, including block caving, room and pillar mining, in situ mining, and variations of these methods.