Gold in porphyry copper systems / by Edwin W.Tooker - Washington, D. C. : United States Goverment Printing office, 1990 - 55 p. : il. ; 28 cm. - Geology and resources of gold in the united states / ch.E(U. S. Geological survey Bulletin ; 1857) . Includes bibliographical references Subjects--Topical Terms: Golg ores--West (United States)Copper ores--West (United States)Geology--West (United States)