In this report the Bureau of Mines studies the structure of the mineral industry; reasons, history, and legal aspects of mergers; merger activity in the mining industry; and the effects of mergers on industry structure, profits, and production. Most mineral mergers occurred in the crude petroleum, natural gas, and petroleum refining sectors. Before 1967 horizontal mergers were predominant in the mineral industry. Since that time, the conglomerate merger has been most popular. This study indicated that mineral-oriented companies that merged frequently did no better in areas such as stock prices and earnings per share than did those which relied on internal growth.