EXHIBIT 3

                              AMENDMENT TO BYLAWS
                            OF MAGMA COPPER COMPANY
                            (A DELAWARE CORPORATION)



     Pursuant to the authority granted in the Bylaws, as amended July 22,
1992, of Magma Copper Company, a Delaware corporation, the same are hereby
amended as follows, having been duly approved by the affirmative vote of at
least a majority of all directors of the corporation at a regular meeting of
the Board of Directors held on July 13, 1995.

     Section 2, "Number, Qualification and Term of Office," of Article
III, "Board of Directors,  of the Bylaws is hereby amended in its entirety as
follows:

               SECTION 2. Number, Qualification and Term of Office.  The
               number of directors which shall constitute the whole
               Board shall be not less than three nor more than twelve. 
               The exact number of directors within the minimum and
               maximum limitations specified in the preceding sentence
               is hereby set at 12, and thereafter shall be fixed from
               time to time by the Board of Directors pursuant to a
               resolution adopted by a majority of the Continuing
               Directors (as such term is defined in the restated
               certificate of incorporation).  The Board of Directors
               shall be and is divided into three classes, Class I,
               Class II and Class III.   No one class shall have more
               than one director more than any other class.  If a
               fraction is contained in the quotient arrived at by
               dividing the authorized number of directors by three,
               then if such fraction is one-third, the extra director
               shall be a member of Class II, and if such fraction is
               two-thirds, one of the extra directors shall be a member
               of Class II, and one of the extra directors shall be a
               member of Class I, unless otherwise provided for from
               time to time by resolution of the Board of Directors. 
               Each director shall serve for a term ending on the date
               of the third annual meeting following the annual meeting
               at which such director was elected; provided, however,
               that each initial director in Class I shall serve for a
               term ending on the date of the annual meeting next
               following the end of calendar year 1987; each initial
               director in Class II shall serve for a term ending on the
               date of the annual meeting next following the end of
               calendar year 1988; and each initial director in Class
               III shall serve for a term ending on the date of the
               annual meeting next following the end of calendar year
               1989.  In the event of any increase or decrease in the
               authorized number of directors, the newly created or
               eliminated directorships resulting from such increase or
               decrease shall be apportioned by the Board of Directors
               among the three classes of directors so as to ensure that
               no one class has more than one director more than any
               other class.  Notwithstanding any provisions to the
               contrary contained herein, each director shall serve
               until a successor is elected and qualified or until his
               earlier death, resignation or removal.  Directors need
               not be stockholders.  Unless approved by unanimous vote
               of the Board of Directors, no person shall be qualified
               for nomination, election or appointment to the Board of
               Directors if such person will have attained the age of 70
               prior to the completion of his term in office.

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                        CERTIFICATE OF SECRETARY
                                       
                                       
                                       

            I, Andrew A. Brodkey, do hereby certify that:
       
            1.   I am the duly elected and acting secretary of Magma Copper
Company, a Delaware corporation (the  Corporation ).

            2.   The foregoing Amendment to Bylaws of Magma Copper Company
was duly adopted by the Board of Directors of the Corporation at a regular
meeting held on July 13, 1995.

            3.   The foregoing Amendment to Bylaws, and the  Bylaws as
amended to and including July 22, 1992 (previously filed as Exhibit 3.4 to
the Corporation s 1992 Form 10-K), together constitute the Bylaws of the
Corporation.

            IN WITNESS WHEREOF, I have hereunto subscribed my name and
affixed the seal of the corporation this 13th day of November, 1995.



                           /s/Andrew A. Brodkey
                           --------------------------
                           Andrew A. Brodkey
                           Secretary



[Seal of 
 Magma Copper Company]