EXHIBIT 99.1 AMENDMENT NO. 1 TO AGREEMENT AND PLAN OF MERGER AMENDMENT NO. 1 (this "Amendment No. 1"), dated as of September 27, 1999, amending the Agreement and Plan of Merger (the "Merger Agreement"), dated as of July 15, 1999, among ASARCO CYPRUS...Agreement and Plan of Merger • September 28th, 1999 • Cyprus Amax Minerals Co • Metal mining • Delaware
