UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Grupo México, S.A. de C.V. (“Grupo México”), Grupo Minero México Internacional, S.A. de C.V. (“GMMI”), Americas Mining Corporation (“AMC”), and SPHC II Incorporated (“SPHC II”), (collectively, Grupo México, GMMI, AMC, and SPHC II, the “Reporting Persons”) hereby amend the report on Schedule 13D regarding shares of Southern Peru Copper Corporation (the “Company”), originally filed on January 12, 1996, as further amended on March 6, 1996, on November 19, 1999, on October 13, 2000, on May 17, 2001, on July 16, 2001, on February 11, 2003, on March 31, 2003, on October 25, 2004, on November 1, 2004, on December 23, 2004 and on April 1, 2005 (collectively with this Amendment No. 12, the “Schedule 13D”). Unless otherwise indicated, capitalized terms used but not defined herein shall have the same meanings assigned to them in Schedule 13D.

Item 1.

Security and Issuer

This Schedule 13D relates to the Common Stock of the Company, $0.01 par value per share (the “Common Stock”).

Item 4.

Purpose of Transaction

Item 4 is hereby amended and supplemented by adding the following:

On May 19, 2005, SPHC II voluntarily converted, on a share-for-share basis, all of its 43,348,949 shares of the Company’s Class A Common Stock, 0.01 par value per share (the “Class A Common Stock”) into an equal number of newly-issued shares of fully paid and non-assessable Common Stock.  Simultaneous with SPHC II’s conversion, the other holders of the Class A Common Stock, namely Cerro Trading Company, Inc., SPC Investors, L.L.C., Phelps Dodge Overseas Capital Corporation and Climax Molybdenum B.V., voluntarily converted all of their shares of Class A Common Stock, on a share-for-share basis, into an equal number of newly-issued shares of fully paid and non-assessable Common Stock.  In total, 65,900,833 shares of Class A Common Stock were converted into Common Stock.

Based on information from the Company, as a result of the conversion by all holders, (1) no shares of Class A Common Stock remain outstanding and no shares of Class A Common Stock will be reissued, and (2) the number of authorized shares of Common Stock is now 167,207,640 and there are outstanding 147,248,216 shares of Common Stock.  In addition, the Agreement Among Certain Stockholders of the Company, dated January 2, 1996, as amended, has terminated as a result of the conversion pursuant to section 4.2 thereof. 

Accordingly, the rights of each holder of Class A Common Stock, including SPHC II, (1) to vote as a separate class with respect to the election of directors of the Company, (2) to elect thirteen of the fifteen members of the Board of Directors of the Company (3) and to have five votes per share of Class A Common Stock when voting as a single class with the Common Stock on all matters other than the election of directors have been eliminated. 

Item 5.

Interest in Securities of the Issuer

Item 5 is hereby amended and supplemented by adding the following:

(a, b) As of the date hereof, GM, GMMI, and AMC may each be deemed to beneficially own the 110,556,589 shares of Common Stock, constituting 75.1% of the total Common Stock based on a total of 147,248,216 shares of Common Stock outstanding, as set forth in the Company’s Form 8-K filed on May 20, 2005. 

GM, GMMI, and AMC each have the sole power to vote or direct the vote of 0 Shares; have the shared power to vote or direct the vote of 110,556,589 shares of Common Stock; have the sole power to dispose or direct the disposition of 0 Shares; and have the shared power to dispose or direct the disposition of 110,556,589 shares of Common Stock.

As of the date hereof, SPHC II beneficially owns 43,348,949 shares of Common Stock, constituting 29.4% of the outstanding Common Stock based on a total of 147,248,216 shares of Common Stock outstanding, as set forth in the Company’s Form 8-K filed on May 20, 2005. 

SPHC II has the sole power to vote or direct the vote of 0 shares and the shared power with GM, GMMI and AMC, to vote or direct the vote of 43,348,949 shares of Common Stock; has the sole power to dispose or direct the disposition of 0 shares; and has the shared power with GM, GMMI and AMC, to dispose or direct the disposition of 43,348,949 shares of Common Stock.

(c) The response to Item 4 is incorporated herein by reference in its entirety.

Item 6.

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

The response to Item 4 is incorporated herein by reference in its entirety.

GRUPO MÉXICO, S.A. DE C.V.

/s/ Armando Ortega Gómez

Name: Armando Ortega Gómez

Title: General Counsel

GRUPO MINERO MÉXICO
INTERNATIONAL, S.A. DE C.V.

/s/ Armando Ortega Gómez

Name: Armando Ortega Gómez

Title: General Counsel

AMERICAS MINING CORPORATION

/s/ Ernesto Durán Trinidad

Name: Ernesto Durán Trinidad

Title: President and CFO

SPHC II INCORPORATED

/s/ Ernesto Durán Trinidad

Name: Ernesto Durán Trinidad

Title: Comptroller