<PAGE>
                                                                    Exhibit 10.7

                                                                  EXECUTION COPY

================================================================================

                              COMPLETION GUARANTEE

                                      among

                        SUMITOMO METAL MINING CO., LTD.,
                              as a Parent Company,

                              SUMITOMO CORPORATION,
                              as a Parent Company,

                     COMPANIA DE MINAS BUENAVENTURA S.A.A.,
                              as a Parent Company,

                            PHELPS DODGE CORPORATION,
                              as a Parent Company,

                    JAPAN BANK FOR INTERNATIONAL COOPERATION,
                          as a Senior Facility Lender,

                      SUMITOMO MITSUI BANKING CORPORATION,
                 as a Lead JBIC Arranger and Global Coordinator,

                       THE BANK OF TOKYO-MITSUBISHI, LTD.,
                            as a Lead JBIC Arranger,

                                      KfW,
                          as a Senior Facility Lender,

                             CALYON NEW YORK BRANCH,
       as a Senior Facility Lender, Lead Arranger and Global Coordinator,

                         THE ROYAL BANK OF SCOTLAND PLC,
                 as a Senior Facility Lender and Lead Arranger,

                            THE BANK OF NOVA SCOTIA,
                 as a Senior Facility Lender and Lead Arranger,

                          MIZUHO CORPORATE BANK, LTD.,
                 as a Senior Facility Lender and Lead Arranger,

                                       and

                             CALYON NEW YORK BRANCH,
                             as Administrative Agent

                         Dated as of September 30, 2005

================================================================================
<PAGE>
                                Table of Contents

<TABLE>
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                                    ARTICLE I

                         DEFINITIONS AND INTERPRETATION

1.01   Definitions.......................................................     3
1.02   Interpretation....................................................     4

                                   ARTICLE II

                                   COMPLETION

2.01   Full Completion...................................................     5
2.02   Partial Completion................................................     6
2.03   Completion Certificates...........................................     7
2.04   Waiver of Completion Conditions...................................     8

                                   ARTICLE III

                             COMPLETION UNDERTAKING

3.01   Completion Undertaking............................................     8
3.02   Funding Obligations...............................................     9
3.03   Debt Buy-Down Option..............................................    11

                                   ARTICLE IV

                      GUARANTEE OF SENIOR LOANS OBLIGATIONS

4.01   Guarantee of Senior Loans Obligations.............................    13
4.02   Payments Free and Clear of Taxes, Etc.............................    15
4.03   Subrogation of Parent Companies to Rights of Senior Lenders
       Against Borrower..................................................    16
4.04   Several Obligations...............................................    16

                                    ARTICLE V

                  SUSPENSION AND TERMINATION OF OBLIGATIONS DUE
                       TO EVENT OF POLITICAL FORCE MAJEURE

5.01   Declaration of Event of Political Force Majeure; Suspension of
       Obligations.......................................................    16
5.02   Termination Due to Event of Political Force Majeure...............    16
</TABLE>


                                        i
<PAGE>
                                Table of Contents
                                   (continued)

<TABLE>
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5.03   Notice by Parent Companies of Exercise of Suspension
       or Termination Rights.............................................    17
5.04   Arbitration.......................................................    17
5.05   Reinstatement of Suspended Obligations............................    17
5.06   Limitations on Rights to Suspend or Terminate.....................    18
5.07   Effect of Arbitration on Time Periods.............................    19

                                   ARTICLE VI

             REPRESENTATIONS AND WARRANTIES OF THE PARENT COMPANIES

6.01   Representations and Warranties of the Parent Companies............    19

                                   ARTICLE VII

                        COVENANTS OF THE PARENT COMPANIES

7.01   Net Worth.........................................................    21
7.02   Financial Disclosure..............................................    21

                                  ARTICLE VIII

                             PARENT COMPANY DEFAULTS

8.01   Parent Company Defaults...........................................    22
8.02   Exception to Section 8.01.........................................    23
8.03   Declaration of Event of Default...................................    23
8.04   Cessation of PC Event of Default; Rescission of Acceleration......    24
8.05   Remedies..........................................................    24
8.06   Control of PC Enforcement Action by Administrative Agent..........    25
8.07   Limitation on Enforcement Action..................................    26

                                   ARTICLE IX

                                  MISCELLANEOUS

9.01   Subordination of the Parent Companies.............................    27
9.02   Accession.........................................................    28
9.03   Termination of Agreement..........................................    28
9.04   Currency Equivalents..............................................    28
9.05   GOVERNING LAW.....................................................    28
9.06   Severability......................................................    28
9.07   Entire Agreement..................................................    29
</TABLE>


                                       ii
<PAGE>
                                Table of Contents
                                   (continued)

<TABLE>
<CAPTION>
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9.08   Notices...........................................................    29
9.09   Successors and Assigns............................................    30
9.10   Benefits of Agreement.............................................    31
9.11   Remedies..........................................................    31
9.12   Execution in Counterparts.........................................    31
9.13   Consent to Jurisdiction...........................................    31
9.14   Amendments and Waivers............................................    32
9.15   Effectiveness.....................................................    32
9.16   Arbitration.......................................................    32
9.17   No Trial by Jury..................................................    34
9.18   No Partnership....................................................    34
9.19   Expenses..........................................................    34
9.20   No Immunity.......................................................    34
</TABLE>

Schedule A      Sample Calculation of the Retired Principal Senior Loan Amount

Exhibit A       Terms of Subordination
Exhibit B       Form of Pledge Agreement

Appendix A-1    Form of Production Full Completion Certificate
Appendix A-2    Form of Efficiency Full Completion Certificate
Appendix A-3    Form of Physical Facilities Completion Certificate
Appendix A-4    Form of Insurance Completion Certificate
Appendix A-5    Form of Legal Completion Certificate
Appendix A-6    Form of I.A. Financial Completion Certificate
Appendix A-7    Form of Borrower Financial Completion Certificate
Appendix A-8    Form of Environmental Certificate
Appendix A-9    Form of Production Partial Completion Certificate
Appendix A-10   Form of Efficiency Partial Completion Certificate


                                       iii
<PAGE>
                              COMPLETION GUARANTEE

     This COMPLETION GUARANTEE (this "Agreement"), dated as of September 30,
2005, is made among:

     SUMITOMO METAL MINING CO., LTD., a corporation organized under the laws of
Japan ("SMM");

     SUMITOMO CORPORATION, a corporation organized under the laws of Japan
("SC");

     COMPANIA DE MINAS BUENAVENTURA S.A.A., a Peruvian sociedad anonima abierta
("BVN");

     PHELPS DODGE CORPORATION, a company organized under the laws of the State
of New York ("PDC" and, together with SMM, SC and BVN, the "Parent Companies");

     JAPAN BANK FOR INTERNATIONAL COOPERATION, a Japanese government financial
institution organized under the laws of Japan ("JBIC"), in its capacity as a
Senior Facility Lender;

     SUMITOMO MITSUI BANKING CORPORATION, a stock corporation organized under
the laws of Japan, as lead JBIC arranger and Global Coordinator ("SMBC");

     THE BANK OF TOKYO-MITSUBISHI, LTD., a banking institution organized under
the laws of Japan, as lead JBIC arranger ("BOT-M" and together with SMBC, in
their capacity as lead JBIC arrangers, the "Lead JBIC Arrangers");

     KfW, a public corporation formed under the laws of the Federal Republic of
Germany ("KfW"), in its capacity as a Senior Facility Lender;

     CALYON New York Branch, a licensed branch of a banking corporation
organized and existing under the laws of the French Republic ("Calyon"), in its
capacity as a Senior Facility Lender, Lead Arranger and Global Coordinator;

     THE ROYAL BANK OF SCOTLAND PLC, a public limited company incorporated under
the laws of Scotland ("rbs"), in its capacity as a Senior Facility Lender and
Lead Arranger;

     THE BANK OF NOVA SCOTIA CAPITAL, a Canadian chartered bank, organized under
the laws of Canada ("Scotia Capital"), in its capacity as a Senior Facility
Lender and Lead Arranger;
<PAGE>
     MIZUHO CORPORATE BANK, LTD., a banking institution organized under the laws
of Japan ("Mizuho", and collectively with Calyon, RBS and Scotia Capital, the
"Commercial Banks"), in its capacity as a Senior Facility Lender and Lead
Arranger; and

     CALYON New York Branch, a licensed branch of a banking corporation
organized and existing under the laws of the French Republic, as Administrative
Agent for the Senior Lenders (in such capacity, together with successors and
assignees, the "Administrative Agent").

                                    WHEREAS:

     A. Sociedad Minera Cerro Verde S.A.A. (the "Borrower") proposes to incur
Senior Loans Obligations in order to develop the Sulfide Project at its existing
Mines in the District of Uchumayo and Yarabamba, Province of Arequipa, Republic
of Peru;

     B. On the date hereof, JBIC has entered into the JBIC Loan Agreement with
Borrower, KfW has entered into the KfW Loan Agreement with Borrower and the
Commercial Banks have entered into the Commercial Banks Loan Agreement with
Borrower. Each such agreement reflects, among other terms, (i) the commitment of
each Senior Facility Lender that is a party thereto to make from time to time
Advances to the Borrower in an amount up to its Aggregate Committed Amount and
(ii) the Borrower's agreement to repay such Advances with interest;

     C. On the date hereof, the Borrower, JBIC, the Lead JBIC Arrangers, KfW,
the Commercial Banks, the Global Coordinators, the Lead Arrangers and the
Administrative Agent have entered into the Master Participation Agreement dated
as of the date hereof (the "Master Participation Agreement" or "MPA") which sets
forth various terms for the financing of the development of the Sulfide Project;

     D. The Master Participation Agreement contemplates that the Borrower shall
have the right to issue Peruvian Bonds under a Peruvian Bonds Program and that
the Common Representative shall become a party to this Agreement by entering
into, in its capacity as Common Representative, a New Party Accession Agreement
and thereupon the Common Representative and the Peruvian Bondholders shall have
all the rights and obligations of, respectively, the Common Representative and
the Peruvian Bondholders under this Agreement; and

     E. The Parent Companies have authorized the execution and delivery of this
Agreement to undertake specified obligations to induce the Senior Lenders to
make Senior Loans to the Borrower.

     NOW, THEREFORE, in consideration of the execution of the Master
Participation Agreement and the Senior Loan Documents by the Senior Lenders, to
induce the Senior Lenders to make Senior Loans thereunder, and for other good
and


                                        2
<PAGE>
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Parent Companies, each of the Lead JBIC Arrangers, each of the
Senior Facility Lenders and the Administrative Agent (each a "CG Party" and
collectively, the "CG Parties", which term shall include the Common
Representative after the Common Representative has become a party to this
Agreement in accordance with Section 9.02(a) and any Replacement Lender or
Bridge Loan Provider after such Replacement Lender or Bridge Loan Provider has
become a party to this Agreement in accordance with Section 9.02(b)) agree as
follows:

                                    ARTICLE I

                         DEFINITIONS AND INTERPRETATION

     1.01 Definitions. Unless the context shall otherwise require, or unless
otherwise defined herein, capitalized terms used herein shall have the meanings
assigned to them in Schedule Z to the Master Security Agreement, dated as of the
date hereof, among the Borrower, the Senior Lenders, the Lead JBIC Arrangers,
the Global Coordinators, the Lead Arrangers, the Administrative Agent, the
Trustee, the Offshore Collateral Agent and the Onshore Collateral Agent.

     "Accelerated Parent Company": a Parent Company with respect to which a
Completion Guarantee Acceleration Event has occurred.

     "Completion Certificates": collectively, the Full Completion Variable
Certificates, the Partial Completion Variable Certificates and the Non-Variable
Certificates.

     "Completion Guarantee Acceleration Event": with respect to any Parent
Company, either (i) such Parent Company commences a proceeding under any
applicable bankruptcy, reorganization, arrangement, readjustment of debt, relief
of debtors, dissolution, insolvency, liquidation or similar law (whether now or
hereafter in effect) relating to itself, or is declared bankrupt, is dissolved
by reason of insolvency or makes a general assignment for the benefit of
creditors, or any action is taken by it for the purpose of effecting any of the
foregoing or by a receiver, custodian or trustee or other officer or
representative of a court or of creditors; or there is commenced against it any
such proceeding which remains undismissed for 60 days or (ii) such Parent
Company fails to maintain a Net Worth at least equal to U.S.$1,500,000,000, in
the case of PDC, Y90,000,000,000 in the case of SMM or SC and U.S.$300,000,000
in the case of BVN.

     "Completion Guarantee Obligations": the obligations of the Parent Companies
under this Agreement.

     "Completion Release Date": the date of achievement of either (i) Full
Completion or (ii) Partial Completion.


                                        3
<PAGE>
     "Defaulting Parent Company": a Parent Company with respect to which a PC
Event of Default has occurred.

     "Guarantee Release Date": either (i) the date of achievement of Full
Completion, with respect to all Parent Companies, or (ii) the date of occurrence
of the Debt Buy-Down Release Date as contemplated under Section 3.03(d) of the
Completion Guarantee.

     "Net Worth": with respect to any Person, its net worth calculated in
accordance with United States GAAP.

     "Non-Accelerated Parent Companies": Parent Companies that are not
Accelerated Parent Companies.

     "PC Agreements": collectively, the Completion Guarantee and the Transfer
Restrictions Agreement.

     "PC Enforcement Action": means taking any legal, equitable or other
remedial action provided under the Completion Guarantee or the Transfer
Restrictions Agreement or any other action available under applicable law
against a given Defaulting Parent Company, provided that actions taken by Senior
Lenders pursuant to Section 8.06 of this Agreement shall not constitute "PC
Enforcement Action".

     "Pro Rata Share": with respect to (i) PDC, 57.720%, (ii) SMM, 18.104%,
(iii) SC, 4.526% and (iv) BVN, 19.650%.

     "Subordinated Lender": a Person making a Subordinated Loan to the Borrower.

     "Subordinated Loans": unsecured indebtedness of the Borrower to a
Subordinated Lender, whether presently outstanding or hereafter created,
incurred or assumed, that is subordinated to the Senior Loans on the terms set
forth in Exhibit A to the Completion Guarantee.

     "Target Completion Date": the date that is 42 months after the signing date
of the MPA.

     "TRA Parties": the meaning given in preamble of the TRA.

     "Transfer Restrictions Agreement" or "TRA": the Transfer Restrictions
Agreement, dated as of the date of the MPA, among the TRA Parties.

     1.02 Interpretation. In this Agreement and in the Appendices hereto, except
to the extent that the context otherwise requires:


                                        4
<PAGE>
          (a) the Table of Contents, Articles and Section headings are for
     convenience of reference only and shall not affect the interpretation of
     this Agreement;

          (b) unless otherwise specified, references to Articles, Sections,
     clauses, Exhibits, Schedules and Appendices are references to Articles,
     Sections, clauses Exhibits and Schedules of, and Appendices to, this
     Agreement;

          (c) references to any document or agreement, including this Agreement,
     shall be deemed to include references to such document or agreement as
     amended, supplemented or replaced and in effect from time to time in
     accordance with its terms and subject to compliance with the requirements
     set forth herein and therein;

          (d) references to any party to this Agreement or any other document or
     agreement or to any other Person shall include its successors and permitted
     assigns;

          (e) when used in this Agreement, the words "including", "includes" and
     "include" shall be deemed to be followed in each instance by the words
     "without limitation";

          (f) when used in this Agreement, the words "herein", "hereby",
     "hereunder", "hereof", "hereto", "hereinbefore", and "hereinafter", and
     words of similar import, shall refer to this Agreement in its entirety and
     not to any particular section, subsection, paragraph, sub-paragraph, clause
     or other subdivision, exhibit, schedule or appendix of this Agreement; and

          (g) when used herein, the singular shall include the plural, the
     plural shall include the singular and the use of any gender shall include
     all genders, unless the context requires otherwise.

                                   ARTICLE II

                                   COMPLETION

     2.01 Full Completion. For purposes of this Agreement, "Full Completion"
shall (subject to Section 2.03(b) hereof) occur upon the delivery by the
Borrower to the Administrative Agent of the certificates and other documents,
listed in clauses (a) through (h) below (each certificate listed in clause (a)
and (b), a "Full Completion Variable Certificate", and each certificate listed
in clause (c) through (h), a "Non-Variable Certificate").


                                       5
<PAGE>
     (a) Production Full Completion Certificate. A "Production Full Completion
Certificate" executed by an Authorized Officer of the Borrower and verified by
the Independent Engineer, substantially in the form set forth in Appendix A-1.

     (b) Efficiency Full Completion Certificate. An "Efficiency Full Completion
Certificate" executed by an Authorized Officer of the Borrower and verified by
the Independent Engineer, substantially in the form set forth in Appendix A-2.

     (c) Physical Facilities Completion Certificate. A "Physical Facilities
Completion Certificate" executed by an Authorized Officer of the Borrower and
verified by the Independent Engineer, substantially in the form set forth in
Appendix A-3.

     (d) Insurance Completion Certificate. An "Insurance Completion Certificate"
executed by an Authorized Officer of the Borrower and verified by the Insurance
Consultant, substantially in the form set forth in Appendix A-4.

     (e) Legal Completion Certificate. A "Legal Completion Certificate" executed
by an Authorized Officer of the Borrower, substantially in the form set forth in
Appendix A-5.

     (f) I.A. Financial Completion Certificate. An "I.A. Financial Completion
Certificate" executed by the Independent Accountant, substantially in the form
set forth in Appendix A-6.

     (g) Borrower Financial Completion Certificate. A "Borrower Financial
Completion Certificate" executed by an Authorized Officer of the Borrower,
substantially in the form set forth in Appendix A-7.

     (h) Environmental Certificate. An "Environmental Certificate" executed by
an Authorized Officer of the Borrower and verified by the Independent Engineer,
substantially in the form set forth in Appendix A-8.

     2.02 Partial Completion. For purposes of this Agreement, "Partial
Completion" shall (subject to Section 2.03(b) hereof) occur upon the delivery by
the Borrower to the Administrative Agent of (i) the certificates and other
documents, listed in clauses (a) and (b) below (each, a "Partial Completion
Variable Certificate") and (ii) the Non-Variable Certificates.

     (a) Production Partial Completion Certificate. A "Production Partial
Completion Certificate" executed by an Authorized Officer of the Borrower and
verified by the Independent Engineer, substantially in the form set forth in
Appendix A-9.


                                       6
<PAGE>
     (b) Efficiency Partial Completion Certificate. An "Efficiency Partial
Completion Certificate" executed by an Authorized Officer of the Borrower and
verified by the Independent Engineer, substantially in the form set forth in
Appendix A-10.

     2.03 Completion Certificates.

     (a) The Borrower may deliver the Completion Certificates, together or
separately in any order and at any time and from time to time, provided that (i)
the Non-Variable Certificates (other than the Physical Facilities Completion
Certificate) each shall be dated as of a date not earlier than the latest of the
dates of the Variable Certificates; (ii) the Legal Completion Certificate and
the Environmental Certificate shall be dated as of the same date and (iii) the
Completion Test Period for the purpose of each Variable Certificate shall be the
same, it being understood that such period may be different from the testing
period used for the purpose of the Physical Facilities Completion Certificate.

     (b) Each Completion Certificate will be conclusive as to the matters
covered therein, unless within 30 Business Days after delivery of the latest of
the Completion Certificates the Administrative Agent (acting upon written
instructions from any three Senior Lenders) notifies the Borrower that it
intends to commence an arbitration proceeding in accordance with Section 9.16 (a
"Completion Arbitration") and within 30 Business Days of such notification the
Administrative Agent (acting upon written instructions from any three Senior
Lenders) actually commences such arbitration.

     (c) During the pendency of any Completion Arbitration:

          (i) Full Completion or Partial Completion, as the case may be, shall
     be deemed not to have occurred, unless a revised, or a revised set of,
     Completion Certificate(s) is delivered and not challenged in accordance
     with Section 2.03(b);

          (ii) the Parent Companies shall only be required to make Completion
     Loans pursuant to Section 3.02 to the extent necessary to pay for care and
     maintenance costs of the Borrower that are not otherwise funded; and

          (iii) any payment to be made by a Parent Company pursuant to Article
     IV shall be paid to the Administrative Agent and shall be held by the
     Administrative Agent in escrow pending resolution of the Completion
     Arbitration.

     (d) At the conclusion of a Completion Arbitration,

          (i) If the arbitration panel referred to in Section 9.16 determines
     that a Completion Certificate was false in any material respect as of its
     date, all payments made to the Administrative Agent in escrow pursuant to
     Section 2.03(c)(iii) shall be distributed by the Administrative Agent to
     the Senior


                                       7
<PAGE>
     Lenders entitled to receive such payment pursuant to Article IV. In
     addition, if the challenged Completion Certificate is otherwise determined
     in such arbitration proceeding to satisfy the conditions for such
     certificate to qualify as a Partial Completion Variable Certificate,
     Borrower shall be entitled, during a period of 30 days, to deliver a
     replacement certificate with all of the information being true and correct
     in which case (x) Partial Completion will be deemed to have occurred as of
     the date of delivery of the latest of the Completion Certificates provided
     that the replacement certificate will be deemed delivered as of the date of
     delivery of the certificate so replaced and (y) the period of time allowed
     to the Parent Companies for exercise of the Debt Buy-Down Option pursuant
     to Section 3.03(a) shall be extended, as necessary, so that such period of
     time expires no earlier than the date that is 30 days after the conclusion
     of the Completion Arbitration.

          (ii) If the arbitration panel referred to in Section 9.16 determines
     that Full Completion or Partial Completion, as the case may be, had
     occurred, Full Completion or Partial Completion will be deemed to have
     occurred as of the date of delivery of the latest of the Completion
     Certificates and all payments made by any Parent Company to the
     Administrative Agent in escrow pursuant to Section 2.03(c)(iii), shall be
     returned by the Administrative Agent to such Parent Company together with
     accrued interest thereon.

     2.04 Waiver of Completion Conditions. The Administrative Agent (acting upon
instructions from each Senior Lender) may declare Full Completion or Partial
Completion to have occurred at any time prior to the satisfaction of the
conditions set forth in Section 2.01 or Section 2.02, as the case may be, by
delivering a notice to the Borrower and to each Parent Company, stating that
Full Completion or Partial Completion, as the case may be, has occurred.

                                   ARTICLE III

                             COMPLETION UNDERTAKING

     3.01 Completion Undertaking. Subject to Article V hereof, each Parent
Company undertakes, severally and not jointly, until the Completion Release
Date, to use its reasonable efforts to (i) cause Borrower to construct and
complete the Sulfide Project in all material respects in accordance with the
description of the Sulfide Project set forth in Schedule D to the MPA on or
prior to the Target Completion Date, (ii) cause the Borrower to achieve Full
Completion on or before the Target Completion Date (for the avoidance of doubt,
while it is the intention and objective of the Parent Companies that Full
Completion be achieved and that all commercially reasonable efforts be used to
achieve the same, this provision shall not require any Parent Company to cause
the Borrower to attempt to achieve Full Completion if it is commercially
unreasonable to do so) or (iii) if it is commercially unreasonable to cause the
Borrower to attempt to achieve Full Completion, cause the Borrower to achieve
Partial Completion on or before the


                                        8
<PAGE>
Target Completion Date (for the avoidance of doubt, this provision shall not
require any Parent Company to cause the Borrower to attempt to achieve Partial
Completion if it is commercially unreasonable to do so), provided that this
provision shall not require any Parent Company to provide funding, incur or
guarantee indebtedness or undertake any financial obligation, except as
specifically set forth in Section 3.02. For purposes of this Section 3.01,
neither the level of copper prices at any particular time of itself, nor the
expected return on the incremental investment that may be required to achieve
either Full Completion or Partial Completion shall in and of itself constitute
sufficient grounds for a determination of the commercial reasonableness or
unreasonableness of the efforts to achieve either Full Completion or Partial
Completion, provided that the expected overall rate of return of each Parent
Company on the totality of its investments in the Project, including such
incremental investment, may be a sufficient factor in the determination of the
commercial reasonableness of efforts to achieve either Full Completion or
Partial Completion. The Parent Companies shall notify the Administrative Agent
in writing within 3 Business Days from the making of a determination that it is
commercially unreasonable to achieve Full Completion or Partial Completion, as
the case may be.

     3.02 Funding Obligations.

     (a) Subject to Article V hereof, until the Completion Release Date, the
Administrative Agent (acting at the direction of the Majority Lenders) or the
Borrower shall have the right to notify in writing the Parent Companies of the
existence and amount of a shortfall (including as a result of any cost overrun
or shortfall in the amount of cash flow generated from Current Operations as
compared to the amount of funds necessary to achieve Full Completion or Partial
Completion, if the Parent Companies notify the Administrative Agent that, in
accordance with Section 3.01, they have determined in good faith that it is
commercially unreasonable to continue to attempt to achieve Full Completion
(identifying the basis for such conclusion) and will proceed to attempt to
achieve Partial Completion) in available funds (a "Notified Cash Shortfall"),
taking into account all funds available under the Senior Loan Documents to the
Borrower and all anticipated revenues from Current Operations, to satisfy
amounts to become due and payable in the next Calculation Period to either (i)
achieve Full Completion or Partial Completion, as the case may be, or (ii) pay
Senior Loans Obligations then due and payable. The notice delivered by the
Administrative Agent or the Borrower, as the case may be, shall separately
identify the amounts of any shortfall required to complete the Sulfide Project,
in accordance with Section 3.01, and the amounts required to pay Senior Loans
Obligations, and shall serve as a request by the Administrative Agent or the
Borrower, as the case may be, for such additional funding to be provided by the
Parent Companies in accordance with Section 3.02(c).

     (b) Within 30 Business Days of receipt of such notification, any Parent
Company shall have the right to contest such determination and ask the
Independent Engineer to make a determination as to the existence and amount of
such Notified Cash


                                        9
<PAGE>
Shortfall. If the Independent Engineer confirms the existence and amount of a
Notified Cash Shortfall or if the Parent Companies do not contest a Notified
Cash Shortfall determination by the Administrative Agent or the Borrower within
the above mentioned 30 Business Days period, such Notified Cash Shortfall shall
become a "Confirmed Cash Shortfall".

     (c) Subject to Article V hereof, each Parent Company shall be required to
contribute (directly or indirectly) additional funds to the Borrower in the form
of loans, ("Completion Loans"), in an amount equal to its Pro Rata Share of any
Confirmed Cash Shortfall. With respect to a given Confirmed Cash Shortfall, the
Parent Companies, at their discretion, shall decide the timing for the making of
such Completion Loans, so long as the proceeds thereof are contributed to the
Borrower by the Parent Companies at the same time and no later than the time
funds, not otherwise available under the Senior Loan Documents to the Borrower,
are required for the purpose set forth in clauses (i) and (ii) of paragraph (a).

     (d) The rights of each Parent Company against the Borrower with respect to
such Parent Company's Completion Loans shall be subordinated to the rights of
the Senior Lenders in accordance with the Terms of Subordination attached as
Exhibit A.

     (e) At the time of the making of any Completion Loan, the Parent Companies
shall enter into a pledge agreement substantially in the form attached hereto as
Exhibit B to pledge the Completion Loans to secure the Senior Loans.

     (f) The obligations of the Parent Companies to make Completion Loans shall
be several and shall terminate upon the occurrence of the Completion Release
Date.

     (g) Notwithstanding anything in this Agreement to the contrary, to the
extent that a Parent Company:

          (i) makes a Completion Loan relating to Section 3.02(a)(ii) the
     proceeds of which are applied to pay Senior Loans Obligations, such Parent
     Company's Completion Guarantee Obligation shall be deemed to be satisfied
     in respect of the Senior Loans Obligations to which such Confirmed Cash
     Shortfall relates, regardless of whether other Parent Companies make
     corresponding Completion Loans in respect of such Confirmed Cash Shortfall;

          (ii) provides the Borrower with, or directly purchases, its Pro Rata
     Share of the Purchased Principal Senior Loan Amounts pursuant to Section
     3.03(b), (x) such Parent Company's Completion Guarantee Obligation shall be
     deemed to be satisfied and (y) such Parent Company shall have no obligation
     to make a Completion Loan relating to Section 3.02(a)(ii), in each case, in
     respect of the Senior Loans Obligations to which such purchase relates,
     regardless of whether other Parent Companies provide the Borrower with
     their


                                       10
<PAGE>
     respective Pro Rata Share, or make corresponding purchases, in respect of
     such Senior Loans Obligations, and

          (iii) makes a payment under its Completion Guarantee Obligation,
     pursuant to Section 4.01(a), such Parent Company shall have no obligation
     to make a Completion Loan relating to Section 3.02(a)(ii) in respect of
     Senior Loans Obligations to which such Completion Guarantee Obligation
     payment relates, regardless of whether other Parent Companies have made
     corresponding Completion Guarantee Obligation payments.

     3.03 Debt Buy-Down Option.

     (a) If Full Completion is not achieved on or before the Target Completion
Date, upon the achievement of Partial Completion on or prior to the Target
Completion Date the Parent Companies shall have the right, but not the
obligation, by delivery of written notice (the "Debt Buy-Down Notice") to the
Administrative Agent, no later than the date that is 30 Business Days before the
date that is twelve (12) months following the Target Completion Date, to
purchase, or cause to be prepaid, Senior Facility Loans (on a pro rata basis
based on the Outstanding Advance Amount of each Senior Facility Lender) in an
aggregate amount (the "Retired Principal Senior Loan Amount") sufficient to
ensure that the projected Annual DSCR with respect to each Calculation Period is
at least equal to 1.5X. The agreed methodology for the calculation of the
Retired Principal Senior Loan Amount is attached as Schedule A.

     (b) The Parent Companies shall cause the Borrower to calculate, and notify
to the Administrative Agent and the Senior Facility Lenders for their review,
the projected Annual DSCR and the Maximum Allowed Debt Amount. In case of
disagreement, the Administrative Agent (on its own behalf or upon the
instructions of any Senior Facility Lender) shall have the right within 10
Business Days to request that the Independent Public Accountants verify in
writing such computations and provide alternate computations, if necessary. The
Borrower and the Administrative Agent (acting at the direction of any Senior
Facility Lender) shall both instruct the Independent Public Accountants to
complete its verification and provide such alternate computations, if necessary,
within 10 Business Days from the date of such instruction. The calculation made
by the Independent Public Accountants shall be final absent manifest error.

     (c) Concurrently with the delivery by the Parent Companies of the Debt
Buy-Down Notice, the Parent Companies shall cause the Borrower to notify to the
Administrative Agent and the Senior Facility Lenders the Retired Principal
Senior Loan Amount. Within 15 Business Days from the Buy-Down Notice Date, the
Parent Companies shall have the right to notify in writing the Administrative
Agent of the aggregate amount (up to the Retired Principal Senior Loan Amount)
of Senior Facility Loans that they intend to purchase (the "Purchased Principal
Senior Loan Amount"). On the date that is 30 Business Days after the date of the
Debt Buy-Down Notice or on such


                                       11
<PAGE>
other date (at least 15 Business Days following the date of the notification
contemplated in the previous sentence) as the Parent Companies and the
Administrative Agent (acting upon instructions of the Supermajority Facility
Lenders) agree (the "Debt Buy-Down Closing Date"):

          (i) Each Parent Company shall (directly or through a third party, in
     which case each reference to such Parent Company in subsection (c)(ii),
     (d)(ii) and (e) below shall be read as a reference to such third party)
     purchase its Pro Rata Share of the Purchased Principal Senior Loan Amount
     (on a pro rata basis among the Senior Facility Lenders based on their
     respective Outstanding Advance Amounts) at a purchase price (payable in
     cash and in immediately available funds) equal to 100% of such principal
     amount to be paid plus accrued and unpaid interest to the Debt Buy-Down
     Closing Date;

          (ii) each Senior Facility Lender shall sell to each Parent Company
     such portion of the Purchased Principal Senior Loan Amount to be purchased
     by such Parent Company from such Senior Facility Lender on such date and
     shall execute such documents as may be necessary to document the sale by
     such Senior Facility Lender to the Parent Companies of its pro rata share
     of the Purchased Principal Senior Loan Amount; and each Parent Company
     shall enter into a pledge agreement pledging such portion of the Purchased
     Principal Senior Loan Amount purchased by such Parent Company to secure the
     Senior Loans, and confirming the subordination of such Purchased Principal
     Senior Loan Amount as required by Section 3.02(e), in substantially the
     form attached as Exhibit B; and

          (iii) each Parent Company may cause the Borrower to prepay Senior
     Facility Loans in an amount (the "Prepaid Principal Senior Loan Amount")
     equal to the difference between the Retired Principal Senior Loan Amount
     and the aggregate portion of the Purchased Principal Senior Loan Amount
     purchased by all Parent Companies, provided that upon giving effect to such
     prepayment the Reserve Accounts are fully funded as contemplated in the MSA
     and the Borrower has cash on hand in the Proceeds Account (excluding funds
     credited to the Senior Debt Service Reserve Sub-Account, the Senior Debt
     Accumulation Sub-Account and insurance proceeds credited thereto that are
     subject to Section 3.06(b) of the MPA) to pay for at least 30 days of
     Operating Costs.

     (d) The Debt Buy-Down Release Date shall occur in any of the following
circumstances:

          (i) If the Maximum Allowed Debt Amount is greater than or equal to the
     Calculation Date Outstanding Amount, (x) 10 Business Days after
     notification by the Borrower to the Administrative Agent of its computation
     of the Maximum Allowed Debt Amount, if the Administrative Agent has not
     delivered a written notice requesting the Independent Public Accountants to
     verify such computation


                                       12
<PAGE>
     by such time or (y) upon the notification by the Independent Public
     Accountants of their confirmation that the Maximum Allowed Debt Amount is
     greater than or equal to the Calculation Date Outstanding Amount; and

          (ii) If the Calculation Date Outstanding Amount is greater than the
     Maximum Allowed Debt Amount, (A) on such date as the Post Calculation Date
     Excess Repayment Amount equals or exceeds the Calculation Date Excess
     Amount or (B) on the Debt Buy-Down Closing Date, if the sum of the
     aggregate amount of Senior Facility Loans purchased and paid in full by the
     Parent Companies and the aggregate amount of Senior Facility Loans prepaid
     by the Borrower pursuant to Section 3.06(g) of the MPA, on or prior to such
     date, equals at least the Retired Principal Senior Loan Amount.

     (e) The rights of each Parent Company against the Borrower with respect to
such Parent Company's Purchased Principal Senior Loan Amount shall be
subordinated to the rights of the Senior Lenders in accordance with the Terms of
Subordination attached as Exhibit A.

     (f) The obligations of the Parent Companies on the Debt Buy-Down Closing
Date shall be several and shall terminate upon the occurrence of the Guarantee
Release Date.

                                   ARTICLE IV

                      GUARANTEE OF SENIOR LOANS OBLIGATIONS

     4.01 Guarantee of Senior Loans Obligations.

     (a) Subject to Article V, each Parent Company unconditionally and
irrevocably guarantees to each Senior Lender, on a several basis, the punctual
payment by the Borrower of such Parent Companies' Pro Rata Share of all Senior
Loans Obligations (each such obligation, as it may from time to time be amended
or waived in accordance with the Master Participation Agreement or the Peruvian
Bonds Indenture, as the case may be, a "Guaranteed Obligation"), whether now
existing or hereafter existing or due or to become due, so long as such
Guaranteed Obligations are due and payable on or prior to the Guarantee Release
Date and are not paid by the Borrower when and as the same shall become due and
payable, whether at maturity, upon acceleration or otherwise.

     (b) Each Parent Company agrees that its obligations under this Section 4.01
shall be unconditional and irrevocable, irrespective of the invalidity or
unenforceability of the Guaranteed Obligations, the absence of any action to
enforce the Guaranteed Obligations against Borrower, any waiver or consent by
any Senior Lender with respect to any provision of this Agreement or any other
Financing Document, the recovery of any judgment against the Borrower or any
action to enforce the same, the insolvency or


                                       13
<PAGE>
bankruptcy of the Borrower or any other circumstance which might otherwise
constitute a legal or equitable discharge or defense of a guarantor or surety.
Each Parent Company waives diligence, presentment, demand of payment, filing of
claims with a court in the event of insolvency or bankruptcy of the Borrower,
any right to require a proceeding first against the Borrower or against any
other Person under any guarantee of, or security for any Guaranteed Obligation,
protest, notice and all demands whatsoever or any other circumstance which might
otherwise constitute a legal or equitable discharge or defense of a guarantor or
surety or otherwise impair the right of any Appointed Party or any Senior
Lender.

     (c) Each Parent Company agrees, subject to Article V and to Section
3.02(g), that its obligations under this Article IV with respect to any
Guaranteed Obligation will not be discharged except by complete payment by the
Borrower of such Guaranteed Obligation or by complete payment by such Parent
Company of its Pro Rata Share of any such Guaranteed Obligation. In the event
that any payment made by the Borrower to Senior Lenders in respect of any
Guaranteed Obligation is rescinded or must otherwise be returned for any reason
whatsoever, such payment shall be treated as a Guaranteed Obligation and each
Parent Company shall remain liable for such Guaranteed Obligation to the extent
provided herein as if such payment had not been made and:

          (i) if any of the Parent Companies' obligations under this Completion
     Guarantee have been terminated in accordance with this Agreement, such
     obligations shall be reinstated to the extent necessary for the Parent
     Company to comply with the foregoing provisions of this sentence; and

          (ii) each of the Parent Companies agrees that it will pay or reimburse
     each Appointed Party and each Senior Lender within 30 days of written
     request for its Pro Rata Share of all reasonable and documented costs and
     expenses (including, without limitation, reasonable and documented fees and
     disbursements of counsel) incurred by any such Appointed Party or any such
     Senior Lender, as the case may be, in connection with the rescission or
     restoration of the Completion Guarantee, including any such costs and
     expenses incurred in defending against any claim alleging that any payment
     constituted a preference, fraudulent transfer or similar payment under any
     bankruptcy, insolvency or similar law.

     (d) Each Parent Company agrees that any Senior Lender may at any time and
from time to time, either before or after the maturity thereof, without notice
to or further consent of such Parent Company, extend the time of payment of,
exchange or surrender, or fail to perfect, collateral for, or renew any of the
Guaranteed Obligations owed to it, and may also make any agreement with the
Borrower, for the extension, renewal, payment, compromise, discharge or release
thereof, in whole or in part, or for any modification of the terms thereof or of
any agreement between the Senior Lenders and


                                       14
<PAGE>
the Borrower, without in any way impairing or affecting its obligations pursuant
to this Article IV.

     4.02 Payments Free and Clear of Taxes, Etc.

     (a) Any and all payments made by or on account of a Parent Company to a
Senior Facility Lender on account of a Guaranteed Obligation pursuant to this
Article IV, shall be made free and clear of, and without deduction or
withholding for or on account of, any and all present or future Indemnified
Taxes, now or hereafter imposed, levied, collected, withheld or assessed by any
Governmental Authority in Peru, the United States and Japan, unless such
deduction or withholding is required by applicable Government Rule, in which
case paragraph (b) below shall apply.

     (b) If a Parent Company shall be required by law to deduct any Indemnified
Taxes now or hereafter imposed, levied, collected, withheld or assessed by any
Governmental Authority in Peru, the United States, Germany or Japan from or in
respect of any sum payable hereunder or under the Senior Facility Loan
Agreements, such Parent Company shall, at its option, either (i) pay to the
Senior Facility Lender in respect of which such deduction or withholding is
required to be made, such Additional Tax Amount, as may be necessary so that
after all required deductions and withholdings (including, without limitation,
deductions and withholdings applicable to Additional Tax Amounts), such Senior
Facility Lender receives on the due date thereof an amount equal to the sum it
would have received, had no such deduction or withholding been made, or (ii) in
the case of Peruvian Taxes, assume the payment of the Indemnified Tax and pay
directly the full amount to the tax administration when due in accordance with
Article 47 of the Peruvian Income Tax Act, so that the amount paid to the Senior
Facility Lender equals the amount it would have received if the Borrower or the
Parent Companies (as applicable) had not been required by law to deduct such
Indemnified Tax.

     (c) Each Parent Company will indemnify the Administrative Agent and each
Senior Facility Lender against, and reimburse the Administrative Agent and each
Lender on demand for, any Indemnified Taxes paid directly by the recipient of a
payment made by such Parent Company with respect to which such Indemnified Tax
is levied in circumstances where such Parent Company has failed to comply with
its obligation to pay Additional Tax Amount as contemplated in Section 4.02(b)
and any loss, liability, claim or expense, including interest, penalties,
judgments, costs or disbursements and reasonable and documented legal fees,
which the Administrative Agent or any Senior Facility Lender may incur at any
time arising out of or in connection with any failure of such Parent Company to
make any payment of such Indemnified Taxes when due.

     (d) Each Senior Facility Lender shall, from time to time, following receipt
of a written request therefor by a Parent Company, furnish to such Parent
Company any form or certificate and other assistance reasonably requested that
may be necessary to


                                       15
<PAGE>
establish any available exemption from, or reduction in the amount of,
Indemnified Taxes.

     4.03 Subrogation of Parent Companies to Rights of Senior Lenders Against
Borrower.

     (a) Each Parent Company shall be subrogated to all of the rights of the
Senior Lenders against the Borrower and its properties in respect of any amounts
paid by such Parent Company on account of Guaranteed Obligations under this
Article IV; provided, however, that the rights of each Parent Company on account
of such subrogation shall be subordinated to the Senior Loans in accordance with
the Terms of Subordination set forth as Exhibit A.

     (b) Notwithstanding their subrogation rights, no Parent Company shall have
the right to participate in voting decisions of the Senior Lenders so long as
the Senior Loans remain outstanding.

     4.04 Several Obligations. The obligations of the Parent Companies under
this Article IV shall be several and shall terminate upon the occurrence of the
Guarantee Release Date.

                                   ARTICLE V

                    SUSPENSION AND TERMINATION OF OBLIGATIONS
                     DUE TO EVENT OF POLITICAL FORCE MAJEURE

     5.01 Declaration of Event of Political Force Majeure; Suspension of
Obligations. Upon the Continuance of an Event of Political Force Majeure, the
Parent Companies shall have the right to declare that an Event of Political
Force Majeure has occurred and is Continuing by delivering a notice in
accordance with Section 5.03. In the event an Event of Political Force Majeure
is declared under this Section, or by the Senior Facility Lenders in accordance
with Section 11.01 of the Master Participation Agreement, the Completion
Guarantee Obligations shall be suspended automatically (subject to reinstatement
in accordance with Section 5.05 or termination in accordance with Section 5.02).

     5.02 Termination Due to Event of Political Force Majeure. Subject to
Section 5.05, the Parent Companies shall have the right, by delivering a notice
in accordance with Section 5.03, to terminate their respective Completion
Guarantee Obligations, at the election of the Parent Companies, if:

          (i) the Completion Guarantee Obligations shall have been suspended in
     accordance with Section 5.01, and


                                       16
<PAGE>
          (ii) an Event of Political Force Majeure shall have occurred and be
     Continuing for a period of 360 days following such declaration.

     5.03 Notice by Parent Companies of Exercise of Suspension or Termination
Rights. In order for the Parent Companies to declare that an Event of Political
Force Majeure has occurred and is Continuing or to terminate their Completion
Guarantee Obligations pursuant to Section 5.02, the Parent Companies shall
deliver a certificate to each Senior Lender, setting forth in reasonable detail,
as applicable, (i) the events, conditions, circumstances or occurrences that
constitute an Event of Political Force Majeure, (ii) the type of Event of
Political Force Majeure which has occurred, (iii) the date as of which such
Event of Political Force Majeure has occurred, (iv) the provision hereunder
pursuant to which the Completion Guarantee Obligations are to be suspended or
terminated and (v) in the event of termination under Section 5.02, that such
Event of Political Force Majeure has Continued for the time period specified in
such clause.

     5.04 Arbitration. The Administrative Agent (acting pursuant to instructions
from the Majority Lenders) shall have 60 days after receipt of a certificate
delivered under Section 5.03 to deliver a notice to the Parent Companies to the
effect that the Senior Lenders (i) disagree that an Event of Political Force
Majeure has occurred and is Continuing and (ii) intend to commence arbitration
proceedings under Section 9.16 within 45 days of such notice. Each such notice
shall state in reasonable detail the bases for the Senior Lenders' disagreement.
If the Administrative Agent does not timely deliver a notice under this Section
or if such arbitration is not timely commenced by the Administrative Agent, a
certificate delivered under Section 5.03 shall be considered determinative of
the items addressed therein. Pending resolution of any arbitration proceedings,
the Completion Guarantee Obligations shall remain suspended unless such
Completion Guarantee Obligations are otherwise reinstated pursuant to Section
5.05.

     5.05 Reinstatement of Suspended Obligations.

     (a) The Completion Guarantee Obligations, if suspended in accordance with
Section 5.01 (and not terminated under Section 5.02), shall be reinstated in
full force and effect, and shall be enforceable as if no such suspension had
occurred, upon the earlier of (i) cessation of the Event of Political Force
Majeure giving rise to such suspension or (ii) determination by an arbitral
tribunal that the particular event or condition does not constitute an Event of
Political Force Majeure or that such event or condition has ceased. Thereafter,
the Completion Guarantee Obligations shall be reinstated in full force and
effect (unless and except to the extent that at such time the Completion
Guarantee Obligations shall have been suspended or terminated based upon a
different Event of Political Force Majeure).

     (b) If an Event of Political Force Majeure declared under Section 5.01 has
ceased, the Parent Companies shall immediately deliver a notice to the
Administrative Agent declaring that such Event of Political Force Majeure has
ceased. In the event a


                                       17
<PAGE>
cessation notice is delivered under the preceding sentence, the Event of
Political Force Majeure shall be considered to have ceased (and the Completion
Guarantee Obligations unless otherwise suspended or terminated in accordance
with this Agreement shall be reinstated in full force and effect).

     (c) If the Parent Companies have not delivered such a notice, and the
Majority Lenders believe that such Event of Political Force Majeure has ceased,
the Majority Lenders may instruct the Administrative Agent to deliver to the
Parent Companies a notice stating that such Senior Lenders have determined that
such Event of Political Force Majeure has ceased. The notice delivered by the
Administrative Agent shall state in reasonable detail the bases for such Senior
Lender's determination. Within 30 days following delivery to the Parent
Companies of such notice, the Parent Companies may deliver to the Administrative
Agent, a notice stating that they disagree that such Event of Political Force
Majeure has ceased and intend to commence arbitration proceedings within 30 days
from the date of such notice.

          Such notice shall state in reasonable detail the bases for the Parent
Companies' disagreement. Any such arbitration shall be conducted as provided in
Section 9.16. The Parent Companies' Completion Guarantee Obligations shall
remain suspended pending resolution of the arbitration proceeding unless such
Completion Guarantee Obligations are otherwise reinstated or terminated pursuant
to this Article V.

          If such arbitration is commenced within such 30 days and the
arbitrators rule in favor of the Parent Companies, the Parent Companies'
Completion Guarantee Obligations shall remain suspended or be terminated, as the
case may be. If such arbitration is not commenced within such 30 days or the
arbitrators rule that such Event of Political Force Majeure has ceased, the
Parent Companies' Completion Guarantee Obligations shall be reinstated in full
force and effect and shall be enforceable as if no suspension had occurred
(unless and except to the extent that at such time (i) the Completion Guarantee
Obligations shall have been suspended or terminated based upon a different Event
of Political Force Majeure, or (ii) the Completion Guarantee Obligations have
been suspended, based upon the suspension by a Senior Lender, pursuant to
Section 11.01 of the Master Participation Agreement, of its obligations to make
additional Senior Loans, based upon a different Event of Political Force
Majeure).

     5.06 Limitations on Rights to Suspend or Terminate. Notwithstanding any
other provision of this Agreement, the occurrence of an Event of Political Force
Majeure shall not operate to suspend or terminate the Completion Guarantee
Obligations of the Parent Companies pursuant to this Article V if:

     (a) the occurrence of such Event of Political Force Majeure is proximately
caused by actions or omissions of the Borrower, the Parent Companies or any
Shareholder that constitute a breach in a material respect of any law, statute,
decree, writ or order of any Governmental Authority binding on it and relating
to the Business (except


                                       18
<PAGE>
for contest, or the breach, of any such law, statute, decree, writ or order, the
adoption or application of which would (i) in the reasonable judgment of the
Borrower, the Parent Companies or any Shareholder constitute a breach of, or be
inconsistent with, the Stability Agreement or (ii) constitute an Event of
Political Force Majeure);

     (b) such Event of Political Force Majeure has been voluntarily agreed to
(which for this purpose shall not include coerced agreement), or voluntarily
arranged or provoked by the Borrower, the Parent Companies or any Shareholder or
any Affiliate thereof; or

     (c) the Borrower, the Parent Companies or any Shareholder has failed to
take reasonable precautions or pursue reasonable alternative measures available
to it to prevent or mitigate the effects of such Event of Political Force
Majeure; provided, however, that neither the Borrower, the Parent Companies or
any Shareholder shall be required by this clause (c) to accept, acquiesce in or
agree to any modification of any right, make any payment or concession it is not
legally obligated to make or enter into any settlement, compromise or agreement
with any Governmental Authority, labor union or other Person that it is not
legally obligated to enter into.

provided that this Section shall not apply to actions or omissions of the
Borrower to the extent that the Borrower is not under the control of the
Shareholders as controlling shareholder(s) of the Borrower (other than by reason
of voluntary acts of the Shareholders).

     5.07 Effect of Arbitration on Time Periods. If an arbitration commenced
pursuant to Section 5.04 is pending when the time period set forth in Section
5.02 expires and the Parent Companies deliver a termination certificate in
accordance with Section 5.03, such termination shall not become effective until
the conclusion of such arbitration (and then only if arbitrators rule
termination was permitted under this Agreement).

                                   ARTICLE VI

             REPRESENTATIONS AND WARRANTIES OF THE PARENT COMPANIES

     6.01 Representations and Warranties of the Parent Companies. Each Parent
Company represents and warrants to each Senior Facility Lender with respect to
itself that:

     (a) Organization. It is a corporation duly organized, validly existing and
is in good standing under the laws of the jurisdiction of its incorporation
referred to in the recital of the parties at the beginning of this Agreement.


                                       19
<PAGE>
     (b) Authority. It has full power and authority to execute and deliver this
Agreement and to perform its obligations hereunder in accordance with the terms
provided herein.

     (c) Binding Agreement. This Agreement has been duly authorized, executed
and delivered by it and constitutes a valid and legally binding agreement,
enforceable in accordance with its terms, subject to bankruptcy, insolvency,
fraudulent conveyance, reorganization, moratorium and similar laws of general
applicability relating to or affecting creditors' rights and to general equity
principles.

     (d) Consents and Approvals for this Agreement. All Governmental Approvals
which are necessary for the execution and delivery by it of this Agreement and
the performance of its obligations hereunder have been obtained and are in full
force and effect.

     (e) Conflicts. There is no provision of law, statute, regulation, rule,
order, injunction, decree, writ or judgment, no provision of its organizational
documents and no provision of any mortgage, indenture, contract or agreement
binding on it or affecting its properties, which would prohibit, conflict with
or in any way prevent its execution, delivery, or performance of the terms of
this Agreement.

     (f) No Immunity. Neither it nor any of its assets have any immunity (or
rights to claim that it has immunity) from jurisdiction of any court or from any
legal process (whether through service, notice, attachment prior to judgment,
attachment in aid of execution, execution or otherwise).

     (g) Financial Statements.

          (i) Its consolidated financial statements for the period ended June
     30, 2005 are true, complete and correct and fairly present in all material
     respects its financial condition as of the date thereof, all in accordance
     with Peruvian GAAP for BVN, United States GAAP for PDC and SC and Japanese
     GAAP for SMM (subject to normal year-end adjustments).

          (ii) Except as otherwise disclosed to the Senior Lenders in writing
     prior to the date hereof, since the date of such financial statements there
     has been no material adverse change in such Parent Company's financial
     condition.

     (h) Litigation. There is no action, suit, proceeding or investigation, at
law or in equity, or before any Governmental Authority or other Person, pending
or, to the best knowledge of such Parent Company, threatened, against or
affecting such Parent Company or its assets that (i) questions the validity of
this Agreement or any action taken or to be taken pursuant hereto or thereto, or
(ii) in any case or in the aggregate would


                                       20
<PAGE>
reasonably be expected to result in a material adverse effect on the ability of
such Parent Company to comply with its obligations hereunder.

     (i) Ranking. Its obligations under this Agreement shall rank pari passu
with or senior to all other senior unsecured and unsubordinated obligations of
such Parent Company.

                                   ARTICLE VII

                        COVENANTS OF THE PARENT COMPANIES

     7.01 Net Worth. Until the earlier of (i) Guarantee Release Date and (ii)
the termination of the Completion Guarantee Obligations of a given Parent
Company, each Parent Company shall maintain a Net Worth at least equal to
U.S.$1,500,000,000 in the case of PDC, Y90,000,000,000 in the case of each of
SMM and SC, and U.S.$300,000,000 in the case of BVN.

     7.02 Financial Disclosure. Each Parent Company shall cause to be prepared
and deliver to the Administrative Agent the following financial information, to
the extent that it is not publicly available or filed with any stock exchange:

          (a) As soon as available but in no event more than 60 days after the
     end of each of the first three fiscal quarters of each fiscal year of such
     Parent Company, financial statements of such Parent Company consisting of
     an unaudited balance sheet of such Parent Company as of the close of such
     quarter and unaudited statements of income and expense and changes in
     financial position from the beginning of the then-current fiscal year to
     the close of such quarter, certified by an Authorized Officer of such
     Parent Company; and

          (b) As soon as available but in no event more than 120 days after the
     end of each fiscal year of such Parent Company, audited financial
     statements of such Parent Company consisting of a balance sheet as of the
     end of such fiscal year and a statement of income and expense and changes
     in financial position for such fiscal year, certified by the Independent
     Public Accountant

     The above financial statements shall be prepared in accordance with
Peruvian GAAP for BVN, United States GAAP for PDC and SC and Japanese GAAP for
SMM. No Parent Company shall have responsibility to deliver such financial
statements with respect to any other Parent Company.


                                       21
<PAGE>
                                  ARTICLE VIII

                             PARENT COMPANY DEFAULTS

     8.01 Parent Company Defaults. Subject to Section 8.02, each of the
following events shall be a "PC Event of Default" with respect to the Parent
Company with respect to which such event occurs:

     (a) Payment Default. Any Parent Company fails to pay or cause to be paid,
or to have paid on its behalf, on the date on which the same is due and payable,
any amount payable under Article IV on account of a Guaranteed Obligation (and
no other Parent Company cures such breach in accordance with Section 8.02(b)
hereof), and such failure continues unremedied for (i) in the case of an amount
payable on account of Senior Loans Obligations that is principal, interest or
fees, three (3) Business Days from the date notice of such failure to pay was
received by such Parent Company; and (ii) in the case of an amount payable on
account of any other Senior Loans Obligations, five (5) Business Days from the
date notice of such failure to pay was received by such Parent Company.

     (b) Breach of Representation. A representation or warranty made by a Parent
Company hereunder shall prove to have been false when made in any material
respect and such breach of representation or warranty could reasonably be
expected to have a material adverse effect on the ability of the Parent Company
to comply with its obligations hereunder and is not corrected or cured within 10
Business Days after notice from the Administrative Agent (acting pursuant to
instructions from the Majority Lenders) specifying such breach and requiring
that it be remedied;

     (c) Breach of Covenant.

          (i) A Parent Company fails to comply with any of its covenants set
     forth in Sections 3.01 (Completion Undertaking), 3.02 (Funding
     Obligations), 7.01 (Net Worth) and 7.02 (Financial Disclosure) (and no
     other Parent Company timely cures such breach in accordance with Section
     8.02(b) hereof), and such failure continues unremedied for thirty days
     after notice thereof is given by the Administrative Agent (acting pursuant
     to instructions from the Majority Lenders) specifying such default and
     requiring that it be remedied; or

          (ii) Any of the Shareholders or the Parents is not in compliance with
     its share transfer restrictions set forth in Article II of the Transfer
     Restriction Agreement.

     (d) Bankruptcy. A Completion Guarantee Acceleration Event described in
clause (i) of the definition thereof occurs with respect to a Parent Company.


                                       22
<PAGE>
     (e) Debt Buy-Down Failure. Partial Completion is achieved by the Target
Completion Date and the Parent Companies timely exercise their option to buy
down debt pursuant to Section 3.03 but a Parent Company fails to comply with its
obligations to purchase Senior Facility Loans on the Debt Buy-Down Closing Date
(and no other Parent Company cures such breach in accordance with Section
8.02(b) hereof).

     8.02 Exception to Section 8.01.

     (a) The occurrence and Continuance of any of the events listed in Section
8.01 while a Parent Company's Completion Guarantee Obligations are suspended
under Article V shall not constitute a PC Event of Default with respect to such
Parent Company (although if any such event is Continuing at the time of a
reinstatement of a Parent Company's Completion Guarantee Obligations in
accordance with Section 5.05, such event shall constitute a PC Event of Default
with respect to such Parent Company upon the expiration of any applicable grace
period commencing with the time such Parent Company's Completion Guarantee
Obligations are reinstated in accordance with Section 5.05).

     (b) Each Parent Company shall have the right to cure a PC Event of Default
with respect to another Parent Company. Such right shall include the right to
make payments to the Senior Lenders on behalf of a Defaulting Parent Company.

     8.03 Declaration of Event of Default.

     (a) Upon the receipt by the Administrative Agent of a certificate from any
Senior Lender stating that a PC Event of Default described in Section 8.01(a)
has occurred and remains uncured and identifying the Defaulting Parent Company
or Companies with respect to which such PC Event of Default has occurred, the
Administrative Agent (subject to Section 8.04 hereof), by written notice to the
Parent Companies and each Senior Lender in accordance with Section 9.08, shall
declare that a "PC Event of Default" has occurred with respect to each relevant
Defaulting Parent Company.

     (b) A "PC Event of Default" shall also occur without such declaration or
other notice, upon the occurrence of the PC Event of Default referred to in
Section 8.01(d) hereof with respect to the Parent Company affected by the event
described therein.

     (c) Upon the receipt by the Administrative Agent of a certificate approved
by the Majority Lenders stating that a PC Event of Default other than a PC Event
of Default referred to in Section 8.03(a) or 8.03(b) has occurred and remains
uncured and identifying the Defaulting Parent Company or Companies with respect
to which such PC Event of Default has occurred, the Administrative Agent
(subject to Section 8.04 hereof), by written notice to the Parent Companies and
each Senior Lender in accordance with


                                       23
<PAGE>
Section 9.08, shall declare that a "PC Event of Default" has occurred with
respect to each relevant Defaulting Parent Company.

     8.04 Cessation of PC Event of Default; Rescission of Acceleration.

     (a) Cessation of PC Event of Default. (i) Any Senior Lender that has given,
or approved, a certificate or declared a PC Event of Default pursuant to Section
8.03 hereof agrees promptly to notify the Administrative Agent upon the
cessation of the PC Event of Default to which such certificate related of which
such Senior Lender has knowledge and (ii) so long as any PC Event of Default
described in clause (a) of Section 8.01 shall have been fully cured, the
Majority Lenders, in their discretion, may notify the Administrative Agent upon
the cessation of the PC Event of Default to which any certificate given or
approved pursuant to Section 8.03 relate and of which the Majority Lenders have
knowledge. Any notice given pursuant to this Section 8.04 is a "PC Cessation
Notice". The Administrative Agent shall promptly forward such PC Cessation
Notice to each Parent Company in accordance with Section 9.08. A PC Cessation
Notice shall be effective, (x) if it relates to a PC Event of Default declared
under Section 8.01(a), upon receipt by the Parent Companies, if it is approved
by the Senior Lender that has declared such PC Event of Default or the Majority
Lenders (in accordance with this Section 8.04(a)), and (y) otherwise, upon
receipt by the Parent Companies, if it is approved by the Majority Lenders.

     (b) Rescission of Acceleration. Upon the delivery of a PC Cessation Notice
to the Administrative Agent pursuant to clause (a) above, (i) the Requisite
Lenders giving such PC Cessation Notice (in the case of a PC Cessation Notice
that relates to a PC Event of Default declared pursuant to Section 8.03(a)
hereof) or (ii) the Majority Lenders (in the case of a PC Cessation Notice that
relates to any other PC Event of Default), as the case may be, may, in its or
their discretion, rescind and annul any acceleration (made during the
Continuance of such PC Event of Default) of Guaranteed Obligations, in which
case the Defaulting Parent Company shall be released from its obligations to pay
such accelerated Guaranteed Obligations, provided that no such rescission or
annulment described in this Section 8.04(b) shall (x) require any Senior Lender
to return any amount received by it during the Continuance of such PC Event of
Default and (y) affect the declaration of a PC Event of Default or the exercise
of any remedies exercisable upon the occurrence of such subsequent PC Event of
Default or impair any right of any Senior Lender with respect thereto.

     8.05 Remedies.

     (a) Subject to Section 8.02, at any time during the Continuance of a PC
Event of Default described in Section 8.01(a), which has been declared pursuant
to Section 8.03(a) hereof, the Administrative Agent, acting upon instructions
from the Majority Lenders, shall have the right by written notice to the
Defaulting Parent Company to require the Defaulting Parent Company to
immediately pay to such Senior


                                       24
<PAGE>
Lender such Parent Company's Pro Rata Share of such Senior Lender's Outstanding
Advance Amount, without further notice and without presentment, demand, protest
or other notice of any kind, all of which are hereby expressly waived by the
Defaulting Parent Company.

     (b) Subject to Section 8.02, at any time upon the occurrence of the PC
Event of Default described in Section 8.01(d) hereof with respect to a
Defaulting Parent Company, such Defaulting Parent Company shall be immediately
required to pay its Pro Rata Share of all Senior Lenders' Outstanding Advance
Amounts, without further notice and without presentment, demand, protest or
other notice of any kind, all of which are hereby expressly waived by the
Defaulting Parent Company.

     (c) Subject to Section 8.02, at any time upon the occurrence of a PC Event
of Default (other than a PC Event of Default described in Section 8.01(a) or
8.01(d)) with respect to a Defaulting Parent Company, the Administrative Agent
(acting upon instructions from the Majority Lenders) shall have the right to
require such Defaulting Parent Company to immediately pay its Pro Rata Share of
all Senior Lenders' Outstanding Advance Amounts, without further notice and
without presentment, demand, protest or other notice of any kind, all of which
are hereby expressly waived by the Defaulting Parent Company.

     (d) Subject to Section 8.02, (i) upon the occurrence of any PC Event of
Default described in Section 8.01(a), the Majority Lenders, (ii) upon the
occurrence of the PC Event of Default described in Section 8.01(d), any Senior
Lender and (iii) upon the occurrence of a PC Event of Default (other than a PC
Event of Default described in Section 8.01(a) or 8.01(d)), the Majority Lenders,
in each case, shall have the right to request the Administrative Agent to take
any and all PC Enforcement Actions by delivering a notice identified as a Parent
Company enforcement direction (a "PC Enforcement Direction").

     8.06 Control of PC Enforcement Action by Administrative Agent. If the
Senior Lenders have sent to the Administrative Agent a PC Enforcement Direction
(the Senior Lenders sending such PC Enforcement Direction, the "PC Enforcing
Lenders"), together with an indemnity or other arrangement to reimburse
satisfactory to the Administrative Agent, provided that neither the Peruvian
Bondholders nor the Common Representative shall be required to indemnify the
Administrative Agent in an amount in excess of the proceeds recovered by the
Common Representative on behalf of the Peruvian Bondholders as a result of such
PC Enforcement Action, then:

          (i) The Administrative Agent shall exercise its rights and powers
     vested in it by this Agreement or by the Transfer Restrictions Agreement
     which it is directed by the PC Enforcing Lenders to exercise against the
     Parent Companies and shall not be liable with respect to any action taken
     or omitted to be taken by it in accordance with such PC Enforcement
     Direction; and


                                       25
<PAGE>
          (ii) The PC Enforcing Lenders shall have the right to direct the time,
     method and place of conducting any proceeding for any remedy available to
     the Administrative Agent, or exercising any power conferred upon the
     Administrative Agent hereunder; provided that (i) such direction shall not
     be in conflict with applicable law, this Agreement or any of the other
     Financing Documents and (ii) the Administrative Agent may take any other
     action incidental to carrying out any such direction.

     8.07 Limitation on Enforcement Action.

     (a) No Senior Lender (except by a PC Enforcement Direction properly taken
hereunder or as provided in this Section) shall have the right in respect of
this Agreement or the Transfer Restrictions Agreement to take any PC Enforcement
Action against the Parent Companies, it being understood and intended that no
Senior Lender shall have any rights in any manner whatsoever to affect, disturb
or prejudice the rights of any of the other Senior Lenders, or to obtain or seek
to obtain priority or preference over any other Senior Lender or to enforce any
rights under this Agreement or the Transfer Restrictions Agreement, except in
the manner herein provided.

     (b) Notwithstanding the provisions of paragraph (a) above, each Senior
Lender shall have the right, without the consent of or participation by the
Administrative Agent or any other Senior Lender, when permitted under the terms
of this Agreement or the Transfer Restrictions Agreement, to (i) institute any
proceeding, judicial or otherwise against any Defaulting Parent Companies (other
than a proceeding under bankruptcy law or other reorganization, arrangement,
rearrangement of debt, relief of debtors, dissolution, insolvency, liquidation
or similar law or for the appointment of a receiver, trustee or other officer or
representative of a court or creditors), and to (ii) obtain a judgment and/or an
order of attachment or other similar document issued by any court of competent
jurisdiction, in each case, to the extent, but only to the extent, necessary to
preserve such Senior Lender's rights against such Defaulting Parent Company
which are in peril of losing their legal validity due to the impending or
anticipated expiration of any applicable statute of limitations or similar law
limiting the period of time in which legal action must be taken or commenced;
provided that such Senior Lender may not take any action to enforce any such
judgment or order of attachment against such Defaulting Parent Company.

     (c) If (i) the PC Enforcing Lenders have given a PC Enforcement Direction
to the Administrative Agent, (ii) the PC Enforcing Lenders have offered to the
Administrative Agent an indemnity or other arrangement to reimburse reasonably
satisfactory to it against the costs, expenses and liabilities to be incurred in
compliance with such direction, and (iii) the Administrative Agent, for 30 days
after its receipt of such PC Enforcement Direction, has failed to institute any
proceeding, then, unless a successor Administrative Agent shall have been
appointed within 30 days thereafter pursuant to the Master Participation
Agreement, the PC Enforcing Lenders acting by


                                       26
<PAGE>
themselves may take, or agree that one or more PC Enforcing Lender may take, any
PC Enforcement Action that the Administrative Agent is authorized to take
hereunder.

     (d) At any time after a PC Enforcement Direction has been properly given,
Senior Lenders may agree upon any other manner or method of preserving,
enforcing or collecting Guaranteed Obligations, whether or not provided for or
contemplated herein, provided that (i) any such agreement which would result in
payment or satisfaction of Guaranteed Obligations on a basis which does not
constitute a Pro Rata Payment shall require the consent of all Senior Lenders,
(ii) the Administrative Agent shall be notified of any such agreement and (iii)
any such agreement shall not adversely affect any of the Administrative Agent's
rights or indemnities under this Agreement or any Financing Document or enlarge
its duties hereunder or thereunder.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.01 Subordination of the Parent Companies. The rights of each Parent
Company against the Borrower with respect to Completion Loans, Purchased
Principal Senior Loan Amount and resulting from any amounts paid by such Parent
Company on account of Guaranteed Obligations under Article IV or Article VIII
(collectively, the "PC Reimbursement Rights") shall be pledged for the benefit
of the Senior Lenders and shall be subordinated to the rights of the Senior
Lenders in accordance with the Terms of Subordination attached in Exhibit A. The
Parent Companies acknowledge and agree that all payments by the Borrower to the
Parent Companies on account of PC Reimbursement Rights shall be Restricted
Payments and shall be made only to the extent the Borrower is allowed to make
Restricted Payments pursuant to the Master Participation Agreement (a "Permitted
Subordinated Payment") and that they shall not initiate any proceedings against
the Borrower with respect to the Collateral until payment in full of all Senior
Loans. In the event that, notwithstanding the foregoing, a Parent Company
receives on account or in respect of its PC Reimbursement Rights any
distribution of assets by the Borrower or payment by or on behalf of the
Borrower of any character, whether in cash, securities or other property, that
is not a Permitted Subordinated Payment, it shall hold in trust (as property of
the Senior Lenders) for the benefit of, and shall, no later than five Business
Days after receipt thereof, pay over or deliver to, the Senior Lenders such
distribution or payment in the form received (except for the endorsement or
assignment by a Parent Company where necessary) for application in accordance
with (i) the Master Participation Agreement and the Senior Facility Loan
Agreements, in the case of Senior Facility Lenders Documents or (ii) the
Peruvian Bonds Indenture, in the case of Peruvian Bondholders.


                                       27
<PAGE>
     9.02 Accession.

     (a) On the Bonds Closing Date, if any, the Common Representative shall
become a party to this Agreement by entering into, in its capacity as Common
Representative, a New Party Accession Agreement, and thereupon the Peruvian
Bondholders, acting through the Common Representative, shall collectively have
all the rights and obligations of a Senior Lender.

     (b) A Replacement Lender or a Bridge Loan Provider, as the case may be, may
become a party to this Agreement by entering into a New Party Accession
Agreement and thereupon such Replacement Lender or Bridge Loan Provider, as the
case may be, shall have all the rights and obligations of a Senior Facility
Lender.

     9.03 Termination of Agreement.

     (a) This Agreement shall terminate as to any Parent Company upon the
earliest of (i) 30 Business Days after Full Completion, (ii) the occurrence of
the Debt Buy-Down Release Date, (iii) the termination of the obligations of the
Parent Companies in accordance with Section 5.02, (iv) after the Availability
Period End Date or the earlier termination by the Senior Lenders of their
Commitments, full payment by such Parent Company of its Pro Rata Share of the
Guaranteed Obligations or full payment by the Borrower of all Senior Loans
Obligations, and (v) the date on which the Master Security Agreement shall
terminate in accordance with its terms, provided that in the case of a
termination pursuant to clause (i) or (ii), if the Senior Lenders timely
initiate a Completion Arbitration, this Agreement shall survive until such
Completion Arbitration is finally resolved.

     (b) Upon the termination of this Agreement, all of the obligations of each
Parent Company under this Agreement shall terminate, and no Parent Company shall
have any further liability hereunder to the Senior Lenders, except with respect
to obligations that arose prior to the termination of this Agreement and
obligations provided under Sections 4.02, 9.05, 9.16 and 9.18, which shall
survive any such termination.

     9.04 Currency Equivalents. Calculation of currency equivalents shall be as
set forth in Section 12.06 of the Master Participation Agreement.

     9.05 GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

     9.06 Severability. If any provision of this Agreement shall be invalid,
illegal or unenforceable, the CG Parties agree to the fullest extent they may
effectively do so that the validity, legality and enforceability of the
remaining provisions shall not in any way


                                       28
<PAGE>
be affected or impaired thereby, and the invalidity of a particular provision in
a particular jurisdiction shall not invalidate such provision in any other
jurisdiction.

     9.07 Entire Agreement. This Agreement and the other PC Agreements
constitute the entire agreement and understanding, and supersede all prior
agreements and understandings (both written and oral), between the Parent
Companies and the Senior Lenders with respect to the financing by the Senior
Lenders of the Sulfide Project and there are no warranties, representations or
other agreements between the CG Parties hereto in connection with the subject
matter hereof except as specifically set forth herein and therein.

     9.08 Notices. Any notice, request, demand, consent, designation, direction,
instruction, certificate, report or other communication to be given hereunder
shall be given in the English language and will be duly given when delivered in
writing or sent by electronic mail confirmed by facsimile transmission (with
written confirmation of receipt, which confirmation may be by facsimile
transmission) (provided that a notice sent by electronic mail shall be duly
given only at the time the facsimile transmission confirming the same is sent)
or facsimile transmission (with written confirmation of receipt, which
confirmation may be by facsimile transmission) to a party at its address and
facsimile transmission numbers as indicated below or to such other address as
may be furnished for this purpose by such party (any such communication that is
not in writing shall be confirmed in writing):

     If to PDC, at:

          Phelps Dodge Tower
          1 North Central Avenue
          Phoenix, Arizona 85004
          U.S.A.
          Attention: Treasurer
          Telephone: (602) 366-8100
          Facsimile: (602) 366-8150

     If to SMMC, at:

          11-3, 5-Chome, Shimbashi
          Minato-ku, Tokyo 105
          Japan
          Attention: Mineral Resources Division
          Telephone: 81-3-3436-7805
          Facsimile: 81-3-3436-7737


                                       29
<PAGE>
     If to SC, at:

          11-1, Kandanishikicho 3-Chome
          Chiyoda-ku, Tokyo 101
          Japan
          Attention: Non-Ferrous Raw Materials Dept.
          Telephone: 81-3-3296-3382
          Facsimile: 81-3-3296-3289

     If to BVN, at:

          Cia. De Minas Buenaventura S.A.A.
          Carlos Villaran 790
          Urb, Santa Catalina, Lima 13, Peru
          Attention: President
          Telecopier: (51)-1-471-7349

     If to a Senior Lender or to the Administrative Agent, at the address or
telex or facsimile numbers set forth in Section 9.04 of the Master Security
Agreement.

     Any notice to be delivered, determination to be made or action to be taken
by the Parent Companies under this Agreement shall be delivered, made or taken
on behalf of the Parent Companies by PDC, unless PDC, SMM, SC and BVN jointly
notify the Administrative Agent otherwise.

     9.09 Successors and Assigns.

     (a) This Agreement shall be binding upon and inure to the benefit of the
Parent Companies, the Administrative Agent and the Senior Lenders and their
respective successors and assigns, except that the Parent Companies may not
assign or transfer any of their rights or obligations under this Agreement
without the prior written consent of the Administrative Agent (acting upon
instructions from each Senior Lender).

     (b) The Common Representative and/or Replacement Lender shall become a CG
Party as contemplated under Section 9.02.

     (c) The rights of a Peruvian Bondholder shall be transferred to a
transferee of Peruvian Bonds.

     (d) Upon prior written notice to each Parent Company and the Administrative
Agent, each Senior Facility Lender may assign its rights hereunder to any other
lender, to which such Senior Facility Lender makes a transfer of an Advance
permitted under Section 12.13 of the Master Participation Agreement.


                                       30
<PAGE>
     9.10 Benefits of Agreement. Nothing in this Agreement, express or implied,
shall give to any Person, other than the CG Parties and their successors and
permitted assigns, any benefit or any legal or equitable right or remedy under
this Agreement.

     9.11 Remedies.

     (a) Other than as stated expressly herein, no remedy herein conferred upon
the Senior Lenders is intended to be exclusive of any other remedy and each and
every such remedy shall be cumulative and shall be in addition to every other
remedy given hereunder or now or hereafter existing at law or in equity or by
statute or otherwise.

     (b) No failure on the part of any Senior Lender to exercise and no delay in
exercising, and no course of dealing with respect to, any right, power, or
privilege under this Agreement shall operate as a waiver thereof nor shall any
single or partial exercise of any right, power or privilege under any such
document preclude any other or further exercise thereof or the exercise of any
other right, power or privilege. No Senior Lender shall be responsible for the
failure of any other Senior Lender to perform its obligations hereunder or under
any Senior Loan Agreement.

     (c) In case any Senior Lender shall have proceeded to enforce any right,
remedy or power under this Agreement and the proceeding for the enforcement
thereof shall have been discontinued or abandoned for any reason or shall have
been determined adversely to such Senior Lender, then and in every such case the
Borrower and the Senior Lenders shall, subject to any effect of or determination
in such proceeding, severally and respectively be restored to their former
positions and rights hereunder.

     9.12 Execution in Counterparts. This Agreement may be executed in any
number of counterparts and by the different CG Parties on separate counterparts,
each of which when so executed and delivered shall be an original, but all the
counterparts shall together constitute one and the same instrument.

     9.13 Consent to Jurisdiction.

     (a) Each Parent Company hereby irrevocably consents and agrees, for the
benefit of each party hereto, that any legal action, suit or proceeding against
it with respect to its obligations, liabilities or any other matter under or
arising out of or in connection with this Agreement may be brought in any
Federal or State court located in New York County in the City of New York and
hereby irrevocably accepts and submits to the non-exclusive jurisdiction of such
court with respect to any such action, suit or proceeding. Each Parent Company
hereby waives any objection which it may now or hereafter have to the laying of
venue of any of the aforesaid actions, suits or proceedings, brought in any such
court and hereby further waives and agrees not to plead or claim in any such
court that any such action, suit or proceeding brought therein has been brought
in an inconvenient forum.


                                       31
<PAGE>
     (b) Each Parent Company hereby irrevocably appoints CT Corporation, with
offices at the date of this Agreement at 111 Eighth Avenue, New York, New York,
U.S.A., as its authorized agent on which any and all legal process may be served
in any such action, suit or proceeding brought in any Federal or State court
located in New York County in the City of New York. Each Parent Company agrees
that service of process in respect of it upon such agent, together with written
notice of such service given to it in the manner provided in Section 9.08
hereof, shall be deemed to be effective service of process upon it in any such
action, suit or proceeding. Each Parent Company agrees that the failure of such
agent to give notice to it of any such service shall not impair or affect the
validity of such service or any judgment rendered in any action, suit or
proceeding based thereon. If for any reason such agent shall cease to be
available to act as such, each Parent Company agrees to designate a new agent in
New York County in the City of New York, on the terms and for the purposes of
this Section 9.13. Nothing herein shall be deemed to limit the ability of any
party hereto to serve any such legal process in any other manner permitted by
applicable law or to obtain jurisdiction over the Parent Companies or bring
actions, suits or proceedings against them in such other jurisdictions, and in
such manner, as may be permitted by applicable law.

     9.14 Amendments and Waivers.

     (a) Neither this Agreement nor any terms hereof may be amended,
supplemented or modified other than pursuant to a written instrument executed by
(i) each Parent Company and (ii) the Administrative Agent, acting in accordance
with Section 6.03 of the Master Security Agreement.

     (b) No waiver by any CG Party of any of its rights, powers and privileges
under this Agreement shall be effective other than pursuant to a written
instrument executed by the CG Party waiving such right, power or privilege,
except that a waiver of rights, powers and privileges by the Senior Lenders can
be executed by the Administrative Agent acting in accordance with Section 6.03
of the Master Security Agreement.

     9.15 Effectiveness. This Agreement shall come into full force and effect
upon its execution and delivery by each of the CG Parties named on the signature
pages hereof.

     9.16 Arbitration.

     (a) Notwithstanding Section 9.13, any dispute regarding (i) the occurrence,
continuance or cessation of an Event of Political Force Majeure or (ii) the
accuracy of a Completion Certificate shall be determined by arbitration between
the Parent Companies, on the one hand, and Senior Lenders on the other hand, in
accordance with the UNCITRAL Arbitration Rules in effect on the date the
arbitration is commenced. Such arbitration shall be the exclusive method for
resolution of the dispute, and the determination of the arbitrators shall be
final and binding (except to the extent there exist


                                       32
<PAGE>
grounds for modification, vacatur, remand, nonenforcement or similar judicial
action respecting an award under the applicable laws governing the recognition
or enforcement of arbitral awards) on the Parent Companies and all Senior
Lenders. The CG Parties agree that, subject to those laws, they will give
conclusive effect to the arbitrators' determination and award and that judgment
thereon may be entered by any court having jurisdiction. The arbitral tribunal's
authority, if any, to determine its own jurisdiction does not affect the
competent court's power to review the arbitration award (including as to matters
of the arbitral tribunal's assertion of jurisdiction) nor shall such authority
by the arbitral tribunal deprive an enforcement court of the authority to review
the arbitral tribunal's assertion of jurisdiction. Each CG Party shall bear its
own costs in any such arbitration, provided that, if the arbitral tribunal
concludes that any CG Party shall have acted unreasonably it may, in its
discretion, award costs against such CG Party.

     (b) The number of arbitrators shall be three, each of whom shall be
disinterested in the dispute or controversy and shall be impartial with respect
to all parties hereto and independent thereof. Within 30 days of the initiation
of the arbitration, the Parent Companies and the Administrative Agent (acting
upon instructions from the Majority Lenders) shall each appoint one arbitrator
and the third arbitrator, who shall serve as the chair of the arbitral tribunal,
shall be appointed in accordance with the UNCITRAL Arbitration Rules in effect
on the date the arbitration is commenced. Should the services of an appointing
authority be necessary, the appointing authority shall be the American
Arbitration Association.

     (c) The place of arbitration shall be New York, New York, United States of
America. The arbitration shall be conducted in the English language and any
documents or portions thereof presented at such arbitration in a language other
than English shall be accompanied by an English translation thereof. The
arbitrators shall give effect insofar as possible to the desire of the parties
hereto that the dispute or controversy be resolved in accordance with good
commercial practice. The arbitrators shall decide such dispute in accordance
with the law of the State of New York, without regard to the conflicts of law
principles thereof, provided that the arbitration and this arbitration agreement
shall be governed by Title 9 (Arbitration) of the United States Code.

     (d) If a Parallel Arbitration is commenced under clause (a) of this Section
with respect to a dispute regarding the occurrence, continuance or cessation of
a given Event of Political Force Majeure, and if, at any time, there shall also
be pending a Lead Arbitration with respect to a dispute regarding the
occurrence, continuance or cessation of the same Event of Political Force
Majeure, the Lead Arbitration shall have priority and the parties to the
Parallel Arbitration shall take all reasonable steps to obtain a stay of the
Parallel Arbitration, which stay shall remain in effect pending the issuance of
any award or awards in the Lead Arbitration and, further, pending the conclusion
of any judicial proceedings to enforce, vacate, modify, or remand the award as
provided by law. Subject to the conclusion of those judicial proceedings, if
any, and the rights of the


                                       33
<PAGE>
parties to the Lead Arbitration to contest any arbitral award or its enforcement
as provided by law, any arbitral award entered in the Lead Arbitration shall be
dispositive of any dispute regarding the occurrence, continuance or cessation of
the Event of Political Force Majeure that was the subject of the Parallel
Arbitration and the tribunal in the Parallel Arbitration shall enter into an
award determinative between the CG Parties in accord with the determination in
the Lead Arbitration.

     (e) The CG Parties agree that it is of paramount importance that disputes
regarding the accuracy of Completion Certificates be resolved expeditiously, and
they therefore charge the arbitral tribunal to schedule submissions, adjust the
schedule, set deadlines and otherwise conduct the proceedings in a manner
designed to reach a final award within 45 days from the constitution of the
arbitral tribunal, consistent with the opportunity for the tribunal to fully
inform itself and the right of the CG Parties to be fully heard. The failure of
the arbitral tribunal to reach an award within such period of time will not
affect its jurisdiction or authority to render a valid award.

     9.17 No Trial by Jury. Each Party hereby waives, to the fullest extent
permitted by applicable law, any and all right to trial by jury in any legal
proceeding arising out of or relating to this Agreement or the transactions
contemplated hereby.

     9.18 No Partnership. Nothing contained in this Agreement and no action by
any of the CG Parties is intended to constitute or shall be deemed to constitute
among such CG Parties a partnership, association, joint venture or other entity.

     9.19 Expenses. In the event of a PC Event of Default, such Defaulting
Parent Company shall pay all reasonable out-of-pocket expenses of the
Administrative Agent and the Senior Lenders (including the reasonable fees and
expenses of counsel for the Administrative Agent or Senior Lenders) incurred in
connection with seeking advice with respect to compliance issues hereunder or
the enforcement of this Agreement against it. Each Parent Company that is not in
compliance with its obligations hereunder shall pay all of its pro rata share of
documented out-of-pocket expenses of the Administrative Agent and the Senior
Lenders (including reasonable fees and expenses of legal counsel) incurred in
connection with the enforcement of any provision of this Agreement and the
collection of any amount due hereunder. For the purpose of this provision, the
pro rata share of a non compliant Parent Company shall be determined by dividing
the Pro Rata Share of such Parent Company by the Pro Rata Shares of all
non-compliant Parent Companies.

     9.20 No Immunity. To the extent that any CG Party has or hereafter may
acquire any immunity (sovereign or otherwise), from any legal action, suit or
proceedings, from jurisdiction of any court or from set-off or any legal process
(whether through service or notice, attachment prior to judgment, attachment in
aid of execution of judgment, execution of judgment or otherwise) with respect
to itself or any of its property, such CG Party hereby irrevocably waives and
agrees not to plead or claim such


                                       34
<PAGE>
immunity in respect of its obligations under this Agreement or the subject
matter hereof or thereof (including, without limitation, any obligation for the
payment of money). The CG Parties hereby agree that the waivers set forth in
this Section 9.20 shall have the fullest effect permitted under the Foreign
Sovereign Immunities Act of 1976 of the United States, as amended, and are
intended to be irrevocable and not subject to withdrawal for purposes of such
Act. The foregoing waiver shall constitute a present waiver of immunity at any
time that any action is initiated against such CG Party with respect to this
Agreement.

                  [Remainder of Page Intentionally Left Blank]


                                       35
<PAGE>
     IN WITNESS WHEREOF, the CG Parties have caused this Agreement to be duly
executed as of the date first above written.

                                        SUMITOMO METAL MINING CO., LTD.


                                        By: /s/ Ichiro Abe
                                            ------------------------------------
                                        Name: Ichiro Abe
                                        Title: Managing Executive Officer


                                        SUMITOMO CORPORATION


                                        By: /s/ Mitsuhiko Yamada
                                            ------------------------------------
                                        Name: Mitsuhiko Yamada
                                        Title: Corporate Officer


                                        COMPANIA DE MINAS BUENAVENTURA S.A.A.


                                        By: /s/ Roque Benavides
                                            ------------------------------------
                                        Name: Roque Benavides
                                        Title: President & CEO


                                        PHELPS DODGE CORPORATION


                                        By /s/ Ramiro G. Peru
                                           -------------------------------------
                                        Name: Ramiro G. Peru
                                        Title: Executive Vice President &
                                               Chief Financial Officer


                                        By: /s/ Stanton K. Rideout
                                            ------------------------------------
                                        Name: Stanton K. Rideout
                                        Title: Vice President & Treasurer


                                       36
<PAGE>
                                        JAPAN BANK FOR INTERNATIONAL COOPERATION


                                        By: /s/ Akira Ogawa
                                            ------------------------------------
                                        Name: Akira Ogawa
                                        Title: Director General - Energy and
                                               Natural Resources Finance
                                               Department


                                        SUMITOMO MITSUI BANKING CORPORATION


                                        By: /s/ Takashi Shimahara
                                            ------------------------------------
                                        Name: Takashi Shimahara
                                        Title: Joint General Manager -
                                               Structured Finance Department


                                        THE BANK OF TOKYO-MITSUBISHI, LTD.


                                        By: /s/ Hiroaki Makino
                                            ------------------------------------
                                        Name: Hiroaki Makino
                                        Title: Senior Manager - Structured
                                               Finance Division


                                        KfW


                                        By: /s/ Wolfgang Behler
                                            ------------------------------------
                                        Name: Wolfgang Behler
                                        Title: First Vice President


                                        By: /s/ Stephan Pueschel
                                            ------------------------------------
                                        Name: Stephan Pueschel
                                        Title: Senior Project Manager


                                       37
<PAGE>
                                        CALYON NEW YORK BRANCH


                                        By: /s/ Georges Romano
                                            ------------------------------------
                                        Name: Georges Romano
                                        Title: Managing Director


                                        By: /s/ Samuel Sherman
                                            ------------------------------------
                                        Name: Samuel Sherman
                                        Title: Director


                                        THE ROYAL BANK OF SCOTLAND PLC


                                        By: /s/ Gregor Hamilton
                                            ------------------------------------
                                        Name: Gregor Hamilton
                                        Title: Associate Director


                                        MIZUHO CORPORATE BANK, LTD.


                                        By: /s/ Masatoshi Abe
                                            ------------------------------------
                                        Name: Masatoshi Abe
                                        Title: Senior Vice President


                                        THE BANK OF NOVA SCOTIA


                                        By: /s/ Michael K. Eddy
                                            ------------------------------------
                                        Name: Michael K. Eddy
                                        Title: Director-Mining


                                        By: /s/ Alexander Mihailovich
                                            ------------------------------------
                                        Name: Alexander Mihailovich
                                        Title: Associate


                                       38
<PAGE>
                                        CALYON NEW YORK BRANCH, as
                                        Administrative Agent


                                        By: /s/ Samuel Sherman
                                            ------------------------------------
                                        Name: Samuel Sherman
                                        Title: Director


                                        By: /s/ Ted Vandermel
                                            ------------------------------------
                                        Name: Ted Vandermel
                                        Title: Director


                                       39
<PAGE>
                                                                      Schedule A

                   METHODOLOGY FOR CALCULATION OF THE RETIRED
                          PRINCIPAL SENIOR LOAN AMOUNT

The Retired Principal Senior Loan Amount shall be calculated according to the
following procedure:

-    The values describing Borrower's performance contained in the Financial
     Model on the OpInput sheet will be updated, with the participation and
     concurrence of the Independent Engineer, based on annualized results
     obtained over either (i) the Completion Test Period or (ii) the Completion
     Test Period and the subsequent three-month period, if, during such
     subsequent three-month period, the Borrower continues to operate the
     Business in accordance with the Mine Plan in effect during the Completion
     Test Period and the Independent Engineer has been given an opportunity to
     monitor operations during such period (the period described in (i) or (ii),
     as the case may be, the "Observation Period").

-    The performance values to be updated and their effects on budget amounts
     for future years will be based on an audit of mine and mill production
     records and G&A records, including operating fixed and variable consumption
     items, for the Observation Period. The Independent Engineer will work with
     Borrower's budgeting personnel at the project site, and with Phoenix
     modeling personnel to verify and concur with performance values and effects
     to be input.

-    The Financial Model will be the Financial Model referred to in the MPA, and
     the Mine Plan utilized will be the Current Mine Plan on which the Partial
     Completion Certificate was based.

-    Unit prices for inputs and commodity prices shall be the same as in the
     Base Case Assumptions. Loan margins will be adjusted to reflect the actual
     margins on the Senior Loans. Assumed base interest rates, tax consequences
     and capital expenditure schedules in the Financial Model will remain
     unchanged.

-    If it has been established in a final nonappealable judgment (or in a
     determination by any Governmental Authority that Borrower has not
     challenged or has ceased to challenge) that the exemption from the royalty
     tax is not available with respect to part of the operations of the
     Borrower, the Base Case Assumptions shall be revised to reflect the fact
     that revenues from such operations will be subject to such royalty tax.

-    The Financial Model shall be used to compute the maximum amount of Total
     Debt (the "Maximum Allowed Debt Amount") (Cell labeled "Max Debt" of the


                                       A-1
<PAGE>
     FinAsmps sheet) outstanding as of the last day of the Observation Period
     (the "Calculation Date") that yields an Annual DSCR for each Remaining
     Calculation Year of not less than 1.5X (as per line 80 of the executive
     summary sheet).

-    If the Maximum Allowed Debt Amount is greater than or equal to the
     outstanding principal amount of all Senior Loans (the "Calculation Date
     Outstanding Amount") on the Calculation Date, the Retired Principal Senior
     Loan Amount shall be equal to zero.

-    If the Calculation Date Outstanding Amount is greater than the Maximum
     Allowed Debt Amount:

     (i) the difference between the Calculation Date Outstanding Amount and the
     Maximum Allowed Debt Amount shall be referred to as the "Calculation Date
     Excess Amount";

     (ii) on the date of the Debt Buy-Down Notice (the "Buy-Down Notice Date"),
     the difference (the "Post Calculation Date Excess Repayment Amount")
     between (x) all payments and/or prepayments of principal on the Senior
     Loans made by Borrower between the Calculation Date and the Buy-Down Notice
     Date and (y) all payments of principal that would have been made on the
     Maximum Allowed Debt Amount between the Calculation Date and the Buy-Down
     Notice Date based on the Repayment Schedule shall be calculated; and

     (iii) on the Buy-Down Notice Date, the Retired Principal Senior Loan Amount
     shall be calculated and shall be equal to the difference between the
     Calculation Date Excess Amount and the Post Calculation Date Excess
     Repayment Amount.

-    The Retired Principal Senior Loan Amount shall be applied as a pro-rata
     reduction of all tranches of Senior Facility Loans.


                                      A-2
<PAGE>
                                                                       EXHIBIT A

                             TERMS OF SUBORDINATION

1.   Each of the Subordinated Lender(s) and the Borrower agrees that the
     Subordinated Obligations (as defined below) are and shall be subordinated,
     to the extent and in the manner hereinafter set forth, to the prior payment
     in full of all Senior Loan Obligations. For the purposes of this Agreement,
     the Senior Loan Obligations shall not be deemed to have been paid in full
     until and unless the Senior Lenders have received payment of the Senior
     Loan Obligations in full in cash.

2.   Until all Senior Loan Obligations shall have been paid and satisfied in
     full:

     (a)  The Borrower shall not, directly or indirectly, make any payment of
          principal or interest or any other payment whatsoever on account of,
          or transfer any collateral for the security of any part of, any
          obligations (including, without limitation, all indebtedness, payment
          of principal, interest, fees, expenses and costs, direct or indirect,
          absolute or contingent, due or to become due, now existing or
          hereafter arising) owing to any of the Subordinated Lenders (the
          "Subordinated Obligations") at any time during the Continuance of a
          Borrower Event of Default. If no Borrower Event of Default has
          occurred and is Continuing, the Borrower may make payments on account
          of the Subordinated Obligations only with funds available for
          distribution by the Borrower under Section 4.09 of the Master Security
          Agreement, provided that the Borrower may only pay such Subordinated
          Obligations if and to the extent permitted by Section 7.20 of the
          Master Participation Agreement;

     (b)  No Subordinated Lender shall sue for, or demand or accept from the
          Borrower or any other Person any such payment (in whole or in part) or
          collateral, nor take any other action to enforce or collect upon any
          such payment (in whole or in part) or to enforce its rights in respect
          of the Subordinated Obligations or any security thereof, nor cancel,
          set off or otherwise discharge any part of the Subordinated
          Obligations; and

     (c)  No Subordinated Lender shall otherwise take any actions prejudicial to
          or inconsistent with the Senior Lenders' priority position over the
          Subordinated Lenders with respect to any Subordinated Obligations.

3.   No Subordinated Lender shall commence or join with any other creditor or
     creditors of the Borrower in commencing any bankruptcy, reorganization or


                                        1
<PAGE>
     insolvency proceedings against the Borrower. At any general meeting of
     creditors of the Borrower or in the event of any proceeding, voluntary or
     involuntary, for the distribution, division or application of all or part
     of the assets of the Borrower or the proceeds thereof, whether such
     proceeding be for the liquidation, dissolution or winding up of the
     Borrower or its business, a receivership, insolvency or bankruptcy
     proceeding, an assignment for the benefit of creditors or proceeding by or
     against the Borrower for position or extension or otherwise, if all Senior
     Loan Obligations have not been paid and satisfied in full at the time, the
     Administrative Agent is hereby irrevocably authorized at any such meeting
     or in any such proceeding:

     (a)  To enforce claims comprising the Subordinated Obligations in the name
          of the respective Subordinated Lenders, by proof of debt, proof of
          claim, suit or otherwise;

     (b)  To collect any assets of the Borrower distributed, divided or applied
          by way of dividend or payment, or such securities issued, on account
          of the Subordinated Obligations and apply the same, or the proceeds of
          any realization upon the same that the Administrative Agent in its
          discretion elects to effect, to the Senior Loan Obligations (whether
          or not due) until all the Senior Loan Obligations (whether or not due)
          shall have been paid and satisfied in full (the Administrative Agent
          hereby agreeing to render any surplus to the Subordinated Lenders)
          before any Subordinated Lender shall be entitled to receive any
          payment on account of the Subordinated Obligations;

     (c)  To vote claims comprising the Subordinated Obligations in order to
          accept or reject any plan of partial or complete liquidation,
          reorganization, arrangement, composition or extension; and

     (d)  To take generally any action in connection with any such meeting or
          proceeding to assert, defend or support the position of the
          Subordinated Lenders.

     After the commencement of any such bankruptcy, reorganization or insolvency
     proceeding, each Subordinated Lender may inquire of the Administrative
     Agent in writing whether the Administrative Agent intends to exercise the
     foregoing rights with respect to the Subordinated Obligations. In the event
     that the Administrative Agent fails within a reasonable time after receipt
     of such inquiry (but, in any event, no later than thirty (30) days after
     receipt of such inquiry) either to file a proof of claim with respect to
     the Subordinated Obligations and to furnish a copy thereof to such
     Subordinated Lender, or to inform such Subordinated Lender in writing that
     the Administrative Agent intends to exercise its rights to assert the
     Subordinated Obligations in the manner hereinabove


                                       2
<PAGE>
     provided, such Subordinated Lender may, but shall not be required to,
     proceed to file a proof of claim with respect to its respective
     Subordinated Obligations and take such further steps with respect thereto,
     not inconsistent with the terms hereof, as such Subordinated Lender may
     deem proper. Neither the failure of the Administrative Agent to take any
     actions hereunder nor the exercise of the rights of any of the Subordinated
     Lenders to assert the Subordinated Obligations as hereinabove provided,
     affects or impairs the subordinated nature of any payment or collateral
     which may be received by the Subordinated Lenders.

     Subject to and from and after the payment and satisfaction in full of all
     Senior Loan Obligations, each Subordinated Lender shall be subrogated to
     the rights of the Senior Lenders to receive payments or distributions of
     cash, property or securities of the Borrower applicable to the Senior Loan
     Obligations until all amounts owing on the Subordinated Obligations shall
     be paid in full, it being understood that the provisions herein are
     intended solely for the purpose of defining the relative rights of the
     Subordinated Lenders and the Senior Lenders. Nothing contained herein is
     intended to or shall impair, as between the Borrower and its creditors
     other than the Senior Lenders and the Subordinated Lenders, the obligation
     of the Borrower, which is absolute and unconditional, to pay to the
     Subordinated Lenders the principal of and the premium, if any, and the
     interest on the Subordinated Obligations as and when the same shall become
     due and payable in accordance with its terms, or to affect the relative
     rights of the Subordinated Lenders and creditors of the Borrower other than
     the Senior Lenders.

4.   In the event that any payment on account of, or transfer of any collateral
     as security for any part of, the Subordinated Obligations is received by
     any Subordinated Lender in violation of the terms herein, such payment or
     collateral shall be held in trust for the benefit of the Senior Lenders and
     immediately be paid over or transferred, in the exact form received (except
     for the endorsement or assignment by such Subordinated Lender where
     necessary), to either the Trustee for application pursuant to the Master
     Security Agreement to the payment of all outstanding Senior Loan
     Obligations or the Offshore Collateral Agent as collateral for the Senior
     Loan Obligations. In the event of failure of any such Subordinated Lender
     to make any such endorsement or assignment, the Trustee and the Offshore
     Collateral Agent, as the case may be, are irrevocably authorized to make
     the same.

5.   Each Subordinated Lender agrees that any note, bond or other instrument
     held by it evidencing Subordinated Loans shall bear a prominent legend
     specifying that payment of principal of, interest on or other amount in
     respect of such note, bond or other instrument is subordinated to the
     Senior Loan Obligations on the terms and conditions set forth herein.


                                       3
<PAGE>
6.   So long as any Senior Debt Obligation remains outstanding, neither the
     Subordinated Lenders nor the Borrower will: (i) convert or exchange any of
     the Subordinated Obligations into or for any other indebtedness or equity
     interest or (ii) sell, assign, pledge, encumber or otherwise dispose of any
     of the Subordinated Obligations unless such sale, assignment, pledge,
     encumbrance or disposition is effected in accordance with the provisions of
     the Financing Documents. The Subordinated Lenders and the Borrower agree
     that they will not permit the terms of any Subordinated Obligations to be
     changed without the prior written consent of the Administrative Agent, such
     consent not to be unreasonably withheld or delayed.

7.   The terms of subordination set forth herein shall continue to be effective
     or be reinstated, as the case may be, if, at any time, any payment by the
     Borrower of any of the Senior Loan Obligations is rescinded or must
     otherwise be returned by any of the Senior Lenders or the Administrative
     Agent upon the bankruptcy, reorganization or insolvency of the Borrower or
     otherwise, all as though such payment had not been made.

8.   Each Subordinated Lender may at any time and from time to time, either
     before or after the maturity thereof, without notice to or further consent
     of the Administrative Agent, extend the time of payment of, exchange or
     surrender or fail to act hereunder, or renew any of the Subordinated
     Obligations owed to it, and may also make any agreement with the Borrower,
     for the extension, renewal, payment, compromise, discharge or release
     thereof, in whole or in part, or for any modification of the terms thereof,
     without in any way impairing or affecting its obligations vis-a-vis the
     Senior Lenders pursuant hereto.

9.   The Borrower may agree at any time and from time to time to extend, renew
     or otherwise change the terms of the Senior Loan Obligations without
     impairing or affecting the rights of the Senior Lenders hereunder.

10.  This Agreement shall be governed by and construed in accordance with the
     laws of the State of New York.


                                        4
<PAGE>
                                                                       EXHIBIT B

                 FORM OF PLEDGE AGREEMENT FOR SUBORDINATED LOAN

          This PLEDGE AGREEMENT (this "Agreement"), dated as of [__________], is
made by and between [NAME OF PARENT COMPANY/COMPANIES], a [___________________]
(the "Subordinated Lender"), and Citibank N.A., in its capacity as Offshore
Collateral Agent under the Master Security Agreement (the "Secured Party") for
the Senior Lenders. Each capitalized term used herein without definition shall
have the meaning set forth in, and shall be construed and interpreted in
accordance with, Schedule Z to the Master Security Agreement dated as of
September 30, 2005 among Sociedad Minera Cerro Verde S.A.A., Japan Bank for
International Cooperation, Sumitomo Mitsui Banking Corporation, The Bank of
Tokyo-Mitsubishi, Ltd., KfW, Calyon New York Branch, The Royal Bank of Scotland
plc, The Bank of Nova Scotia, Mizuho Corporate Bank, Ltd., Citibank, N.A., and
Citibank del Peru (as amended from time to time, the "Master Security Agreement"
or "MSA").

          A. The Borrower has entered into the Master Security Agreement (as
amended, modified and supplemented and in effect from time to time the "Master
Security Agreement"), by and among the Borrower, the Secured Party, the Senior
Lenders and various other appointed parties.

          B. The Subordinated Lender and the Borrower have entered into
[SUBORDINATED LOAN OR OTHER AGREEMENT] (as amended, modified and supplemented
from time to time, the "Subordinated Loan Agreement").

          C. The Financing Documents permit the Borrower to enter into the
Subordinated Loan Agreement and incur the loan obligations resulting therefrom
provided that the Subordinated Lender shall pledge for the benefit of the Senior
Lenders to the extent and in the manner hereinafter set forth, all of the
indebtedness and other obligations of the Borrower to the Subordinated Lender
under the Subordinated Loan Agreement.

          NOW THEREFORE, in consideration of the foregoing premises and as an
inducement to the Senior Lenders to grant financial accommodations to the
Borrower and in consideration of the granting thereof, the receipt and adequacy
of which are hereby acknowledged, the parties to this Agreement hereby agree as
follows:

1.   As collateral security for the prompt payment in full when due (whether at
     stated maturity, by acceleration or otherwise) of the Senior Loan
     Obligations and the Borrower's other obligations under the Senior Loan
     Documents, now existing or hereafter arising, to the extent permitted by
     applicable law, the Subordinated Lender hereby grants, transfers and
     assigns to the Secured Party a security interest in all of its right, title
     and interest in and to the Subordinated Loan Agreements and any promissory
     notes issued pursuant thereto (the "Collateral") including, without
     limitation (a) all of its rights to receive moneys due and to become due
     under or pursuant to any Subordinated Loan Agreement or any promissory
     notes issued pursuant thereto, (b) all of its rights to


                                       1
<PAGE>
     receive proceeds of any insurance, payment and/or performance bond,
     indemnity, warranty or - guarantee with respect to any Subordinated Loan
     Agreement or any promissory notes issued pursuant thereto, (c) all of its -
     claims for damages arising out of or for breach of or default under any
     Subordinated Loan Agreement or any promissory notes issued pursuant thereto
     and (d) all of its rights to terminate, amend, supplement, modify or waive
     performance under any - Subordinated Loan Agreement or any promissory notes
     issued pursuant thereto, to perform thereunder and to compel performance
     and otherwise to exercise all remedies thereunder (it being understood
     that, as set forth in Section 3.10(a) of the Master Security Agreement, the
     Secured Party shall not be entitled to exercise such rights granted herein
     until the Senior Lenders have directed the Administrative Agent to
     authorize the Secured Party to take Borrower Enforcement Action with
     respect to the Collateral).

2.   The Subordinated Lender represents and warrants to the Secured Party that:

     (a)  The Subordinated Lender is a corporation duly organized, validly
          existing and is in good standing under the laws of the jurisdiction of
          its incorporation.

     (b)  The Subordinated Lender has full power and authority to enter into
          this Agreement, and to grant to the Secured Party the security
          interests in the Collateral owned by it and to incur the other
          obligations provided for herein.

     (c)  There is no provision of law, statute, regulation, rule, order,
          injunction, decree, writ or judgment, no provision of the
          organizational deeds of such Subordinated Lender and no provision of
          any mortgage, indenture, contract or agreement binding on such
          Subordinated Lender or affecting its properties, that would prohibit
          or conflict with the execution, delivery, or carrying out of the terms
          of this Agreement or the security interests granted hereunder.

     (d)  The Subordinated Lender is the legal and beneficial owner of the
          Subordinated Obligations, free and clear of any Lien, claim, option or
          right of others, except for the security interest created under this
          Agreement.

     (e)  The Subordinated Obligations are evidenced by one or more promissory
          notes and are not in default. All filings and other actions necessary
          to perfect the security interest in the Subordinated Obligations
          created under this Agreement, including the delivery of the promissory
          notes to the Secured Party, have been duly made or taken and are in
          full force and effect. This Agreement creates in favour of the Secured
          Party for the benefit of the Senior Lenders a valid and, together with
          such filings and other actions, perfected first priority security
          interest in the Subordinated Obligations, securing the payment of the
          Senior Loan Obligations.

3.   The Subordinated Lender agrees that, except as permitted pursuant to the
     Transfer Restrictions Agreement, it will not (a) sell, assign, convey,
     transfer or otherwise dispose of, or grant any option with respect to, any
     of the Collateral to any Person, or (b) create or suffer to exist any Lien
     upon or with respect to any of the Subordinated Obligations except for the
     pledge, assignment and security interest created under this Agreement.


                                       2
<PAGE>
4.   The parties hereto agree that in accordance with the terms of Section
     3.10(a) of the MSA, notwithstanding the security interest created hereby in
     the Subordinated Loans and the promissory notes issued pursuant thereto,
     until the Senior Lenders have directed the Administrative Agent to
     authorize the Offshore Collateral Agent to take a Borrower Enforcement
     Action, the Subordinated Lender shall retain and be entitled to exercise
     all of its rights in the Subordinated Loans, including, without limitation,
     the right to receive payments of principal and interest on any Subordinated
     Loan Agreements and promissory notes issued pursuant thereto, when payable
     thereunder.

5.   The Secured Party agrees that in the event of (a) a sale, assignment or any
     other disposal of any or all of the Collateral as permitted pursuant to the
     Transfer Restrictions Agreement or (b) the repayment in full by the
     Borrower of an amount evidenced by a promissory note in accordance with the
     terms thereof, the Secured Party shall, upon written instruction by the
     Subordinated Lender, promptly return the promissory note(s) relating to the
     Collateral sold, assigned or disposed of pursuant to clause (a) or relating
     to the amount repaid pursuant to clause (b), to the Subordinated Lender.

6.   The Secured Party, or any officer or agent thereof, with full power of
     substitution for the Secured Party, as the case may be, is hereby appointed
     the attorney-in-fact of the Subordinated Lender for the purpose of carrying
     out the provisions of this Agreement and taking any action and executing
     any instruments which the Secured Party may deem necessary or advisable to
     accomplish the purposes hereof to the extent it is authorized or directed
     to take such action or execute such instrument pursuant to the terms
     hereof, which appointment as attorney-in-fact is coupled with an interest
     and is irrevocable and, without limiting the generality of the foregoing,
     which appointment hereby gives the Secured Party the power and right on
     behalf of the Subordinated Lender, without notice to or assent by any of
     the foregoing, to the extent permitted by applicable law, to do the
     following when and to the extent it is authorized or directed to do so
     pursuant to the terms of this Agreement or the Master Security Agreement:

     (a)  to ask for, demand, sue for, collect, receive and give acquittance for
          any and all moneys due or to become due with respect to the
          Collateral;

     (b)  to receive, take, endorse, assign and deliver any and all checks,
          notes, drafts, acceptances, documents and other negotiable and
          non-negotiable instruments, documents and chattel paper taken or
          received by the Secured Party in connection with this Agreement;

     (c)  to commence, file, prosecute, defend, settle, compromise or adjust any
          claim, suit, action or proceeding with respect to the Collateral;

     (d)  to sell, transfer, assign or otherwise deal in or with the Collateral
          or any part thereof pursuant to the terms and conditions of this
          Agreement; and

     (e)  to do, at its option and at the expense and for the account of the
          Subordinated Lender at any time or from time to time, all acts and
          things which the Secured


                                       3
<PAGE>
          Party deems necessary to protect or preserve the Collateral and to
          realize upon the Collateral;

     provided, that (i) the Secured Party shall not exercise any of its rights
     under this power of attorney prior to a Borrower Enforcement Direction and
     (ii) prior to exercising such rights, the Secured Party shall notify the
     Subordinated Lender of its receipt of such Borrower Enforcement Direction
     and the contents thereof.

7.   If the Administrative Agent has authorized the Secured Party to take
     Borrower Enforcement Action with respect to the Subordinated Obligations:

     (a)  The Secured Party may exercise in respect of the Subordinated
          Obligations, in addition to other rights and remedies provided for
          herein and in the Master Security Agreement or otherwise available to
          it, all the rights and remedies of a secured party upon default under
          the UCC (whether or not the UCC applies to the affected Subordinated
          Obligations).

     (b)  The Secured Party shall receive all cash proceeds in respect of any
          payment of principal and interest or other realization of all or any
          part of the Subordinated Obligations, in accordance with its terms,
          which shall be applied in accordance with the Master Security
          Agreement.

8.   This Agreement may be executed in any number of counterparts, each of which
     shall be deemed to be an original and shall be binding upon all parties
     hereto, and their successors and assigns.

9.   THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
     LAWS OF THE STATE OF NEW YORK.

10.  If any provision of this Agreement shall be invalid, illegal or
     unenforceable, the parties hereto agree to the fullest extent they may
     effectively do so that the validity, legality and enforceability of the
     remaining provisions shall not in any way be affected or impaired thereby
     and the invalidity of a particular provision in a particular jurisdiction
     shall not invalidate such provision in any other jurisdiction.

11.  This Agreement and the security interests and rights created by and
     pursuant to this Agreement shall terminate upon (a) the payment and
     satisfaction in full of all the Senior Loan Obligations or (b) the sale or
     assignment of the entire Collateral in accordance with Section 5(a), and
     the Secured Party shall, at the expense of the Subordinated Lender, execute
     and deliver a termination statement and such instruments of satisfaction,
     discharge and release of security, including the release of the promissory
     notes to the Subordinated Lender, as may be requested by the Subordinated
     Lender and shall (i) in the case of clause (a) above, pay, assign, transfer
     and deliver to or to the order of the Subordinated Lender all moneys and
     other property held by the Secured Party hereunder after payment in full of
     all Senior Loan Obligations, or (ii) in the case of clause (b) above, shall
     pay, assign, transfer and deliver to or to the order of the Subordinated
     Lender all moneys and other property held by the Secured Party hereunder
     after such sale or assignment of the entire Collateral in accordance with
     Section 5(a).


                                        4
<PAGE>
12.  This Agreement shall continue to be effective or be reinstated, as the case
     may be, if, at any time, any payment of any of the Senior Loan Obligations
     is rescinded or must otherwise be returned by any of the Senior Lenders or
     the Administrative Agent upon the bankruptcy, reorganization or insolvency
     of the Borrower or otherwise, all as though such payment had not been made.

13.  This Agreement constitutes the entire agreement and understanding, and
     supersedes all prior agreements and understandings (both written and oral),
     between the Subordinated Lender and the Secured Party with respect to the
     pledge of the Collateral and there are no warranties, representations or
     other agreements between the parties in connection with the subject matter
     hereof except as specifically set forth herein.

14.  The terms of this Agreement may be waived, altered or supplemented only by
     an instrument in writing duly executed by the parties hereto.

15.  This Agreement is for the benefit of the Secured Party, acting on behalf of
     the Senior Lenders, and not for the benefit of any other Person. This
     Agreement shall be binding upon the Subordinated Lender and its successors
     and assigns and shall inure to the benefit of the successors and assigns of
     the Secured Party.

16.  Any notice, request, demand, consent, designation, direction, instruction,
     certificate, report or other communication to be given hereunder shall be
     given in the English language and will be duly given when delivered in
     writing or facsimile transmission (with written confirmation of receipt,
     which confirmation may be by facsimile transmission) to a party at its
     address and facsimile transmission numbers as indicated below or to such
     other address as may be furnished for this purpose by such party (any such
     communication that is not in writing shall be confirmed in writing),
     provided that any notice, request, demand, consent, designation, direction,
     instruction, certificate, report or other communication sent to the Secured
     Party shall be deemed effective upon actual receipt thereof:

          If to the Subordinated Lender, at:

          [Contact information of the Subordinated Lender]

          If to the Secured Party, at:

          Citibank N.A.
          Citibank Agency & Trust
          388 Greenwich Street
          14th Floor
          New York, NY 10013
          Attention: Jenny Cheng
          Telephone: 212 816 5648
          Facsimile: 212 816 5530


                                       5
<PAGE>
17.

     (a)  The Subordinated Lender hereby irrevocably consents and agrees, for
          the benefit of the Secured Party hereto, that any legal action, suit
          or proceeding against it with respect to its obligations, liabilities
          or any other matter under or arising out of or in connection with this
          Agreement may be brought in any Federal or State court located in New
          York County in the City of New York and hereby irrevocably accepts and
          submits to the non-exclusive jurisdiction of such court with respect
          to any such action, suit or proceeding. Each party hereto hereby
          waives any objection which it may now or hereafter have to the laying
          of venue of any of the aforesaid actions, suits or proceedings brought
          in any such court and hereby further waives and agrees not to plead or
          claim in any such court that any such action, suit or proceeding
          brought therein has been brought in an inconvenient forum.

     (b)  The Subordinated Lender hereby irrevocably appoints CT Corporation in
          New York, NY, as its authorized agent on which any and all legal
          process may be served in any such action, suit or proceeding brought
          in any Federal or State court located in New York County in the City
          of New York. The Subordinated Lender agrees that service of process in
          respect of it upon such agent, together with written notice of such
          service given to it in the manner provided in Section 16 hereof, shall
          be deemed to be effective service of process upon it in any such
          action, suit or proceeding. The Subordinated Lender agrees that the
          failure of such agent to give notice to it of any such service shall
          not impair or affect the validity of such service or any judgment
          rendered in any action, suit or proceeding based thereon. If for any
          reason such agent shall cease to be available to act as such, the
          Subordinated Lender agrees to designate a new agent in New York County
          in the City of New York, on the terms and for the purposes of this
          Section 17. Nothing herein shall be deemed to limit the ability of the
          Secured Party or any Senior Facility Lender to serve any such legal
          process in any other manner permitted by applicable law or to obtain
          jurisdiction over the Subordinated Lender or bring actions, suits or
          proceedings against them in such other jurisdictions, and in such
          manner, as may be permitted by applicable law.

18.  Each party hereby waives, to the fullest extent permitted by applicable
     law, any and all right to trial by jury in any legal proceeding arising out
     of or relating to this Agreement or the transactions contemplated hereby.

19.  To the extent that any party has or hereafter may acquire any immunity
     (sovereign or otherwise), from any legal action, suit or proceedings, from
     jurisdiction of any court or from set-off or any legal process (whether
     service or notice, attachment prior to judgment, attachment in aid of
     execution of judgment, execution of judgment or otherwise) with respect to
     itself or any of its property, such party hereby irrevocably waives and
     agrees not to plead or claim such immunity in respect of its obligations
     under this Agreement or the subject matter hereof (including, without
     limitation, any obligation for the payment of money). The parties hereby
     agree that the waivers set forth in this Section 19 shall have the fullest
     effect permitted under the Foreign Sovereign Immunities


                                       6
<PAGE>
     Act of 1976 of the United States, as amended, and are intended to be
     irrevocable and not subject to withdrawal for purposes of such Act. The
     foregoing waiver shall constitute a present waiver of immunity at any time
     that any action is initiated against such party with respect to this
     Agreement.

20.  The Subordinated Lender agrees to pay or reimburse the Secured Party,
     without duplication, for all of its reasonable costs and expenses incurred
     in connection with this Agreement.

21.  The parties agree to do such further acts and things and to execute and
     deliver such additional agreements and instruments as may be reasonably
     necessary to give effect to the purpose of this Agreement and the parties'
     agreement hereunder.

                             [SIGNATURES TO FOLLOW]


                                       7
<PAGE>
          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed as of the date first above written.

                                        [SUBORDINATED LENDER],


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        CITIBANK N.A., as Secured Party


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------
<PAGE>
                                                                    Appendix A-1
                                                         to Completion Guarantee

                FORM OF PRODUCTION CERTIFICATE - FULL COMPLETION

          I, [NAME OF SENIOR OFFICER], [title of Senior Officer] of the
     Borrower, hereby certify that:

     (a) Attached to this certificate as Annex B are copies of operating
records, bills of lading and other data and documentation relating to production
by the Sulfide Project during the periods referred to in clause (e) below. Such
documentation accurately reflects, in all material respects, the production of
the Sulfide Project during the period to which it relates, and evidences
compliance with the certifications set forth in sections (i) through (vi) of
clause (g) below.

     (b) All sampling procedures relevant to the matters covered by this
certificate were conducted by the Borrower in accordance with standard
international mining practices; all assaying was conducted by the Borrower in
accordance with standard international mining practices. The sampling locations
and laboratory assay procedures have been verified by the Independent Engineer.

     (c) The Independent Engineer was provided with the Borrower's most recently
approved Three Year Budget Plan (the "Reference Budget Plan") that covers the
Completion Test Period, together with (i) the current block model and mine plan
(together, the "Current Mine Plan") related to the Reference Budget Plan and
(ii) the past 12 months' operating reports for the Borrower. The Reference
Budget Plan and the Current Mine Plan are in all material respects consistent
with, and contemplate life-of-loan operating and production results not
materially divergent from those projected in, the Primary Sulfide Mine Plan and
Project Financial Model (together, the "2005 Plan") on which the April 7, 2005
Information Memorandum delivered to the Senior Facility Lenders was based
(except for such material changes thereto, if any, as have been previously
furnished to the Senior Facility Lenders, reported on by the Independent
Engineer, and approved by the Majority Facility Lenders). [SELECT ONE: "The
foregoing certification can be made" OR "The foregoing certification cannot be
made. Accordingly, all subsequent references in this Certificate to "Reference
Budget Plan" and "Current Mine Plan" shall mean the 2005 Plan."]

     (d) The Reference Budget Plan was provided to the Independent Engineer at
least 30 Business Days' prior to the start of the Completion Test Period. Notice
of the start of the Completion Test Period was given to the Independent Engineer
at least 15 days prior to the start of such period. The Current Mine Plan was
substantially adhered to during the Completion Test Period.

     (e) the "Completion Test Period" began on [start date] and ended on [date],
and comprised at least 45 Operating Days falling outside of the traditional
"wet" months of January, February and March.

     (f) For purposes of this certificate,
<PAGE>
          (1)  "Completion Test Period" is defined as a period of 90 Operating
               Days in any 100-day continuous period.


          (2)  "Operating Day" is defined as any day other than a day on which
               (a) the operations of the Sulfide Project ceased for more than 12
               continuous hours due to force majeure or (b) work at the Sulfide
               Project was prohibited by applicable law or labor agreement.

          (3)  "force majeure" is defined as an act of God, labor dispute and
               industrial action of any kind (including, without limitation, a
               strike, interruption, slowdown and other similar action on the
               part of organized labor), a lockout, act of the public enemy, war
               (declared or undeclared), civil war, sabotage, blockade,
               revolution, riot, insurrection, civil disturbance, terrorism,
               epidemic, cyclone, tidal wave, landslide, lightning, earthquake,
               flood, storm, fire, adverse weather conditions, expropriation,
               nationalization, act of eminent domain, laws, rules, regulations
               or orders of governmental authority, acts of other private and
               public companies, explosion, breakage or accident to machinery or
               equipment or pipe or transmission line or other facility not of a
               systemic nature, embargo, inability to obtain or delay in
               obtaining equipment, materials, transport, event of political
               force majeure or any event whether similar to the foregoing or
               not which is not within the reasonable control of the Borrower,
               and which has a material adverse effect on the ability of the
               Borrower to perform its obligations, including, without
               limitation, such event which has a material adverse effect on the
               ability of the Borrower to mine, produce or ship copper
               concentrate.

     (g) COMPLETION TEST.

          During the Completion Test Period, the Borrower achieved the following
     results of operations at the Sulfide Project:

          (1) MINE TEST:

               -    Total mined tonnage (including to and from the ore
                    stockpiles) during the Completion Test Period was at least
                    90% of the planned tonnage for such period as forecast in
                    the Current Mine Plan.


                                      A-1-2
<PAGE>
          (2)  MILL TEST:

               -    The Borrower milled ore (a) during the Completion Test
                    Period at an average rate of at least 90% of 108,000 tonnes
                    per day and (b) during 15 continuous Operating Days within
                    the Completion Test Period at an average rate of at least
                    108,000 tonnes per day.

               -    The Borrower produced copper in concentrate during the
                    Completion Test Period totaling at least 90% of planned
                    tonnes of copper in concentrate as forecast in the Reference
                    Budget Plan for such period.

               -    Copper concentrates produced during the Completion Test
                    Period had an average copper grade at least equal to 90% of
                    planned concentrate grade as forecast in the Reference
                    Budget Plan for such period.

               -    Contained molybdenum recovered in molybdenum concentrate
                    produced during the Completion Test Period was at least 50%
                    of the planned recoverable molybdenum forecast in the
                    Reference Budget Plan for such period.

               -    If the copper head grade during the Completion Test Period
                    was more than 120% of the grade contemplated in the
                    Reference Budget Plan for such period, then mill copper
                    recovery was at least 90% of the recovery forecast in the
                    Reference Budget Plan for such period (with Recovery = 100 x
                    (C/H) x (H-T)/(C-T), where H, T, C are head, tail and
                    concentrate % Cu).

          (3)  INFRASTRUCTURE TEST:

               -    Fresh Water Make-Up. The fresh water pumping system is
                    capable of pumping at a rate at least 100% of required
                    make-up water defined in the water balance calculation based
                    on the Borrower's actual operations, and has pumped at a
                    rate at least 90% of design capacity for at least one hour,
                    and such capability and performance are demonstrated in the
                    results (furnished to the Independent Engineer) of the
                    mechanical completion test performed by Fluor and accepted
                    by the Borrower under the Construction Agreements.

               -    Electrical Supply System. The new installed electrical
                    supply system (substation, power line and power distribution
                    system) has installed capacity to meet at least 90% of the
                    design power


                                      A-1-3
<PAGE>
                    requirements specified in the Fluor scope of work under the
                    Construction Agreements which may be modified from time to
                    time and which shall include the design power requirements
                    specified in the Feasibility Study, and such capacity is
                    demonstrated in the results (furnished to the Independent
                    Engineer) of the mechanical completion test performed by
                    Fluor, and accepted by the Borrower under the Construction
                    Agreements. During the Completion Test Period, 100% of the
                    required power demand for the operation of the Primary
                    Sulfide facilities was provided from the national power grid
                    system.

          (4)  TAILING STORAGE:

               -    Viewed at the end of the Completion Test Period, the tailing
                    production and hydro-cyclones system produced sufficient
                    quantity and quality of sand material (at normal particle
                    size) to allow the dam embankment construction to contain
                    the total volume of tailings produced to the end of the
                    Completion Test Period (including the specified safety
                    margin of freeboard as specified in the design parameters
                    set forth in Feasibility Study, as may be modified by the
                    independent review board); and the to-date history of dam
                    construction, at the beginning and at the end of the
                    Completion Test Period, has been provided to the Independent
                    Engineer to demonstrate the foregoing.

          (5)  SHIPPING AND QUALITY TESTS:

               -    90% of the copper concentrate tonnage produced during the
                    Completion Test Period has been loaded onto ships for
                    shipment (or alternatively loaded onto trucks for transport)
                    to a processor during the 120-day period that includes the
                    Completion Test Period.

               -    For all copper concentrate shipments for which settlement
                    was made during the three-month period ending at the
                    commencement of the Completion Test Period, total penalties
                    (price reductions) assessable under applicable Sales
                    Contracts did not exceed 5% of total sales price of such
                    copper concentrate.


                                      A-1-4
<PAGE>
          (6)  EFFICIENCY TEST:

               -    The aggregate efficiency measure [(described in clause
                    (c)(III) of the Efficiency Test description)] during the
                    Completion Test Period did not exceed 112.5%.

This is the certificate referred to in paragraph (a) of Section 2.01 of the
Completion Guarantee, dated as of September 30, 2005, among the Parent
Companies, the Administrative Agent and the Senior Facility Lenders, as the same
may be amended from time to time (the "Completion Guarantee"). Capitalized terms
used herein, except as otherwise defined herein, shall have the meanings
assigned to them in the Completion Guarantee or, if not defined therein,
Schedule Z to the Master Security Agreement, dated as of September 30, 2005,
among the Borrower, the Senior Lenders, the Lead JBIC Arrangers, the Global
Coordinators, the Lead Arrangers, the Administrative Agent, the Trustee, the
Offshore Collateral Agent and the Collateral Agent, as the same may be amended
from time to time (the "Master Security Agreement").

     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER], on behalf of the Borrower
have caused this certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                      A-1-5
<PAGE>
                                   Annex A to

                             Production Certificate

     [Name of Independent Engineer] a _______________ organized under the laws
of _____________ have performed such inspections, observations, analyses and
other procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex C to the Production
Certificate.

     Based on such procedures, we hereby certify that (1) we have no reason to
believe that any of the certifications of the Borrower set forth hereinabove is
not true and correct in all material respects as of the date hereof, and (2) we
concur with the statement made in the second sentence of paragraph (c) of the
foregoing certificate.

     IN WITNESS WHEREOF, [Name of senior officer of Independent Engineer] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF INDEPENDENT ENGINEER]


                                        By:
                                            ------------------------------------
                                        [Name]
                                               ---------------------------------
                                        [Position]
                                                   -----------------------------


                                      A-1-6
<PAGE>
                                   Annex B to
                             Production Certificate

[Attach copies of operating records, bills of lading and other data and
documentation relating to Sulfide Project production and operations during
relevant period, including data demonstrating compliance with the certifications
set forth in the Production Certificate.]


                                      A-1-7
<PAGE>
                                   Annex C to
                             Production Certificate

                 DESCRIPTION OF INDEPENDENT ENGINEER PROCEDURES

                      [To be completed at time of delivery]


                                      A-1-8
<PAGE>
                                                                    Appendix A-2
                                                         to Completion Guarantee

                FORM OF EFFICIENCY CERTIFICATE - FULL COMPLETION

          I, [NAME OF SENIOR OFFICER], [title of Senior Officer] of the
Borrower, hereby certify that:

     (a) Attached to this certificate as Annex B are copies of operating records
and other data and documentation relating to production by and operation of the
Sulfide Project during the Completion Test Period referred to in clause (b)
below. Such documentation accurately reflects, in all material respects, the
production and operation of the Sulfide Project during the period to which it
relates, and evidences compliance with the certification set forth in clause
(c)(III) below.

     (b) (i) For purposes of this Certificate, the "Completion Test Period" is
the same as the Completion Test Period referred to in the Production Certificate
dated the date hereof provided by the Borrower to the Senior Facility Lenders
(the "Production Certificate").

          (ii) The forecast usage, forecast consumption and forecast
     productivity figures set forth in each test below, identified in bold
     typeface, are based on the 2005 Plan. If the Reference Budget Plan used for
     the Production Certificate is different from the 2005 Plan but has been
     approved or certified (by the Borrower and Independent Engineer) as
     contemplated in clause (c) and Annex A of the Production Certificate, then
     such forecast figures will be adjusted to reflect the differences, provided
     the Independent Engineer concurs with such adjustments.

          (iii) If the actual average mine truck haulage distance during the
     Completion Test Period varies from the forecast average distance by more
     than 10%, then, the forecast usage, forecast consumption and forecast
     productivity figures set forth in each of clauses (A), (C), (D) and (E) of
     the mine test in clause (c)(I) below, identified in bold typeface, will be
     adjusted by that percentage difference.

     (c) EFFICIENCY TESTS

               (I)  MINE. The relevant percentages to be computed (based on
                    actual performance during the Completion Test Period) and
                    relative weightings are the following:

                    (A)  FUEL:
                         Percentage: Average mining fleet diesel consumption per
                         operating hour during the Completion Test Period, in
                         gallons per operating truck hour, as a percentage of
                         the forecast consumption of 41.4 U.S. GAL./hr.
                         Weighting: 10.0%

                    (B)  LOADING:
                         Percentage: Shovel operating hours to total tonnes of
                         material loaded on mine trucks during the Completion
                         Test Period as measured by the mine dispatch system, in
                         mine operating hours to dry metric tonnes, as a
                         percentage of the forecast ratio of 1 hr per 4,329 DMT.
                         Weighting: 6.0%
<PAGE>
                    (C)  HAULAGE:
                         Percentage: Truck operating hours to total tonnes of
                         material hauled from the mine and the ore stockpiles,
                         during the Completion Test Period as measured by the
                         mine dispatch system, in mine operating hours to dry
                         metric tonnes, as a percentage of the forecast ratio of
                         1 hr per 548 DMT.
                         Weighting: 12.0%

                    (D)  LABOR:
                         Percentage: Total mine workforce operating hours to
                         tonnes of material (including ore stockpiles) moved
                         during the Completion Test Period, in mine workforce
                         operating hours to dry metric tonnes, as a percentage
                         of the forecast productivity ratio of 1 hr per 99.5
                         DMT.
                         Weighting: 8.0%

                    (E)  TIRES:
                         Percentage: Average mileage-life per mine truck tire
                         (before replacement), in total tires used to total
                         miles of mine truck haulage over the twelve-months
                         period ending at the end of the Completion Test Period,
                         as a percentage of the forecast rate of 1 tire per
                         64,000MI, provided that the Independent Engineer may
                         agree to a substantially equivalent test.
                         Weighting: 4.0%

               (II) MILL. The relevant percentages to be computed (based on
                    actual performance during the Completion Test Period) and
                    relative weightings are the following:

                    (A)  POWER:
                         Percentage: Average electricity consumption per tonne
                         of ore milled (including, concentrator, water supply
                         and water return) during the Completion Test Period, in
                         kilowatt hours per dry metric tonne of ore milled, as a
                         percentage of the forecast rate of 22 KWH/dmt.
                         Weighting: 33.0%

                    (B)  LABOR:
                         Percentage: Average daily total mill workforce to total
                         tonnes of ore milled during the Completion Test Period,
                         in size of workforce to dry metric tonnes of ore
                         milled, as a percentage of the forecast productivity
                         ratio of 1 worker per 341DMT.
                         Weighting: 12.0%

                    (C)  WATER:
                         Percentage: Average liters of fresh water utilized per
                         tonne of ore milled during the Completion Test Period,
                         in liters per dry metric tonne of ore milled, as a
                         percentage of the forecast usage rate of 516 l/dmt.
                         Weighting: 6.0%


                                      A-2-2
<PAGE>
                    (D)  LIME:
                         Percentage: Average kilograms of lime utilized per
                         tonne of ore milled during the Completion Test Period,
                         in kilograms per dry metric tonne of ore milled, as a
                         percentage of the forecast usage rate of 1.1 KG/dmt.
                         Weighting: 6.0%

                    (E)  FLOCCULANT:
                         Percentage: Average grams of flocculant utilized per
                         tonne of ore milled during the Completion Test Period,
                         in grams per dry metric tonne of ore milled, as a
                         percentage of the forecast usage rate of 14 G/dmt.
                         Weighting: 3.0%

               (III) COMPOSITE TEST. Based on the actual performance of the
                    Sulfide Project during the Completion Test Period, the
                    weighted average of the percentages computed under clauses
                    (A) through (E) of Section I and clauses (A) through (E) of
                    Section II above, combined, did not exceed 112.5%.

This is the certificate referred to in paragraph (b) of Section 2.01 of the
Completion Guarantee, dated as of September 30, 2005, among the Parent
Companies, the Administrative Agent and the Senior Facility Lenders, as the same
may be amended from time to time (the "Completion Guarantee"). Capitalized terms
used herein, except as otherwise defined herein, shall have the meanings
assigned to them in the Completion Guarantee or, if not defined therein,
Schedule Z to the Master Security Agreement, dated as of September 30, 2005,
among the Borrower, the Senior Lenders, the Lead JBIC Arrangers, the Global
Coordinators, the Lead Arrangers, the Administrative Agent, the Trustee, the
Offshore Collateral Agent and the Collateral Agent, as the same may be amended
from time to time (the "Master Security Agreement").

          IN WITNESS WHEREOF, I, [Name of Senior Officer], on behalf of the
Borrower have caused this certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                      A-2-3
<PAGE>
                                   Annex A to

                             Efficiency Certificate

     [NAME OF INDEPENDENT ENGINEER] a _______________ organized under the laws
of _____________ have performed such inspections, observations, analyses and
other procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex C to this certificate.

     Based on such procedures, we hereby certify that (1) we have no reason to
believe that any of the certifications of the Borrower set forth hereinabove is
not true and correct in all material respects as of the date hereof, and (2) we
concur with the adjustments (if any) made to original forecasted figures in
accordance with paragraph (ii) and paragraph (iii) of clause (b) of the
foregoing certificate.

     IN WITNESS WHEREOF, [NAME OF SENIOR OFFICER OF INDEPENDENT ENGINEER] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF INDEPENDENT ENGINEER]


                                        By:
                                            ------------------------------------
                                        [Name]
                                               ---------------------------------
                                        [Position]
                                                   -----------------------------


                                      A-2-4
<PAGE>
                                   Annex B to
                             Efficiency Certificate

[Attach copies of operating records and other data and documentation relating to
Sulfide Project production and operations during relevant period, including data
demonstrating compliance with the certifications set forth in the Efficiency
Certificate.]


                                      A-2-5
<PAGE>
                                   Annex C to
                             Efficiency Certificate

                 DESCRIPTION OF INDEPENDENT ENGINEER PROCEDURES

                      [To be completed at time of delivery]


                                      A-2-6
<PAGE>
                                                                    Appendix A-3
                                                         To Completion Guarantee

                     FORM OF PHYSICAL FACILITIES CERTIFICATE

     I, [NAME OF SENIOR OFFICER], [title of Senior Officer] of the Borrower,
hereby certify on behalf of the Borrower that:

     (a) Notwithstanding anything else herein, any and all of the items of
equipment and facilities described in Annex A of this Appendix A-3, may be
substituted in the actual Physical Facilities Certificate with alternative items
of equipment and facilities having substantially equivalent or better mining and
processing capabilities than those of the listed item, subject to the written
concurrence of the Independent Engineer to be attached hereto.

     (b) (i) Between the dates of [_____] and [_____], [NAMES OF EMPLOYEES OR
AGENTS], [TITLES], inspected the equipment and physical facilities of the
Project. We have considered whether, in our reasonable judgment, the equipment
and physical facilities described in Annex A (the "Physical Facilities") have
been installed and have become operational, in each case at the time of such
inspection. Our work involved inspection of equipment and facilities and
operation thereof, only to the extent necessary to identify such equipment and
facilities and the attributes thereof, if any, referred to in Annex A and to
conclude whether such equipment and facilities have become operational. Such
inspections and observations were those we, in our reasonable judgment, deemed
necessary for the purposes of delivering this certificate.

          (ii) We have noted in the analysis attached hereto as Annex B a
description of the equipment which we identified as meeting the requirement of
each item listed in Annex A, together with a description thereof reasonably
sufficient for purposes of such identification. The equipment measures and
amounts stated in Annex B represent approximate figures and actual measures and
amounts may vary depending upon various factors, including actual
characteristics of available equipment. Where measures and amounts relating to
the actual equipment installed are approximately those set forth in Annex A, we
have deemed the installed equipment to be substantially the same as that
described in Annex A and have stated the relevant amount or measure in the
description included in Annex B.

          (iii) Based on and subject to the foregoing, as of the date hereof,
equipment and physical facilities of the Project substantially the same as the
Physical Facilities have been installed and have become operational.

     (c) As of the date hereof,


                                      A-3-1
<PAGE>
          (i) the Borrower has delivered notification of its acceptance of
delivery of, and its acceptance of substantially all work performed in
connection with, each of the Physical Facilities for which such notification is
required under the contracts or sub-contracts for the delivery, construction or
installation of each such facility, to the relevant contractor or
sub-contractor, in accordance with the contracts or sub-contracts for the
delivery, construction or installation of each such facility (subject to the
exceptions or conditions, if any, contained in such notification of acceptance,
none of which shall have (individually or in the aggregate) a material adverse
effect on the operation of the Project substantially as contemplated in the
Primary Sulfide Mine Plan used by the Sponsors to prepare the Project Financial
Model used for the April 7, 2005 Information Memorandum (the "Primary Sulfide
Mine Plan") and the "Master Participation Agreement" and subject further to such
warranties and similar conditions as are set out in such contracts or
sub-contracts, except for any work the non-acceptance of which will not
(individually or in the aggregate) have a material adverse affect on the
operation of the Project,

          (ii) the Borrower has provided to the Independent Engineer each
certificate of system completion to be delivered by contractors and
sub-contractors in connection with the acceptance of work described herein,

          (iii) substantially all payments required as of the date hereof in
respect of such contracts and sub-contracts have been made and the Borrower has
available the funds necessary to make any remaining payments under such
contracts and sub-contracts (but solely as they relate to the Physical
Facilities described in Annex B) as and when they become due and,

          (iv) as of the date hereof,

               (x) the Physical Facilities have been paid for by the Borrower
          or,

               (y) as to those Physical Facilities which have not been so paid
          for, the Borrower has sufficient funds available to it to make such
          payments.

     (d) As of the date hereof, the items and quantities of capital spares
inventory set forth in Annex C hereto are either on hand at a facility of the
Project in Peru or the Borrower has entered into arrangements to procure such
items in the quantities set forth in such Annex C, and such arrangements shall
have been made pursuant to an established procurement system that will provide
spares and consumables in a sound and efficient manner such that such spares and
consumables can be expected to be on hand at the Project's facilities within 120
days (or, in the case of any items of such inventory which have been taken from
inventory and put into use subsequent to Start-up of Commercial Production, such
longer periods as are required by delivery schedules). As of the date


                                      A-3-2
<PAGE>
hereof, the items and quantities of consumables set forth in Annex C are either
on hand at a facility of the Project in Peru or have been purchased by the
Borrower.

     (e) As of the date hereof, (1) the Physical Facilities includes the four
High Pressure Grinding Rolls (HPGR) and the four Ball Mills constructed and
installed at the Project and (2) the Borrower has delivered (or attached hereto)
a certificate of an authorized officer of the Borrower stating that the Borrower
has paid out the entire contract price.

     Our work for purposes of this certificate did not involve any appraisal of
the quality, actual performance characteristics or operating history or
prospects of the equipment and facilities and, accordingly, this certificate
should not be taken as a representation that such equipment or facilities are
free of defects, will perform at their design or nameplate capacities or will
otherwise function for the purposes for which they were designed or installed.

     This is the certificate referred to in paragraph (c) of Section 2.01 of the
Completion Guarantee, dated as of September 30, 2005, among the Parent
Companies, the Administrative Agent and the Senior Facility Lenders, as the same
may be amended from time to time (the "Completion Guarantee"). Capitalized terms
used herein, except as otherwise defined herein, shall have the meanings
assigned to them in the Completion Guarantee or, if not defined therein, the
meanings assigned to them in Schedule Z to the Master Security Agreement, dated
as of September 30, 2005, among the Borrower, the Senior Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers, the Administrative
Agent, the Trustee, the Offshore Collateral Agent and the Collateral Agent, as
the same may be amended from time to time (the "Master Security Agreement").


                                      A-3-3
<PAGE>
     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER], on behalf of the Borrower
have caused this certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                      A-3-4
<PAGE>
     [NAME OF INDEPENDENT ENGINEER] a _______________ organized under the laws
of _____________ has performed such inspections, observations, analyses and
other procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex D to this certificate. Based
on such procedures, we hereby certify that we have no reason to believe that
each of the certifications of the Borrower set forth hereinabove is not true and
correct in all material respects as of the date hereof.

     We concur with any changes to the Annex A as provided in clause (a) of the
Physical Facilities Certificate.

     In our opinion, the list of Capital Spares and Key Consumable Inventory
attached as Annex C is reasonable.

     IN WITNESS WHEREOF, [NAME OF SENIOR OFFICER OF INDEPENDENT ENGINEER] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF INDEPENDENT ENGINEER]


                                        By:
                                            ------------------------------------
                                        [Name]
                                               ---------------------------------
                                        [Position]
                                                   -----------------------------


                                      A-3-5
<PAGE>
                                                                         Annex A
                                              to Physical Facilities Certificate

                  EQUIPMENT AND PHYSICAL FACILITIES DESCRIPTION

Area 3100 Primary Crushing & Coarse Ore Handling

Area 3100 includes a 500 tonne truck dump box positioned directly above a
gyratory crusher. Crushed ore is reclaimed from a surge pocket beneath the
crusher by a variable-speed apron feeder which transfers ore onto coarse ore
transfer conveyor CV-001. The coarse ore stockpile feed conveyor CV-002 receives
primary crushed ore from CV-001 and discharges it onto the coarse ore stockpile.

The truck dump box, crusher support, surge pocket, apron feeder support, and
area for the tail section of the transfer conveyor are of concrete construction.
A structural steel service tower on the open side of the crusher station houses
the crusher hydraulic room and electrical room. A crusher cab is located at the
top of the service tower adjacent to the truck dump box.

Major equipment includes:

     -    Primary gyratory crusher - FFE 60 inch x 113 inch crusher with 746 kW
          drive motor

     -    Rock breaker - BTI hydraulically operated pedestal mounted breaker

     -    Jib crane - HMB 120t/20t pedestal mounted crane

     -    Apron feeder - FFE 2.7 m wide apron feeder / 320 kW hydraulic drive

     -    Coarse ore transfer conveyor - 1.8 m wide x approximately 100 m long/
          1 x 447 kW

     -    Coarse ore conveyor - 1.8 m wide x approximately 700 m long/ 3 x 1044
          kW

Area 3200 Secondary and Tertiary Crushing and Conveying

Area 3200 includes a reclaim tunnel and four feeders to reclaim primary crushed
ore to feed the secondary/tertiary crushing plant. The crushing plant is an open
structural steel building approximately 70 m x 74 m in footprint. The crushing
plant includes secondary screens and crushers, tertiary HPGR (high pressure
grinding roll) crushers, screens, feeders, conveyors and storage bins. Product
from the tertiary crushers discharges onto a conveyor system to the ball mills.

Major equipment includes:


                                      A-3-6
<PAGE>
     -    Coarse ore reclaim feeders - 4# - FFE 1.8 m wide apron feeders / 150
          kW hydraulic drives

     -    Coarse ore reclaim conveyor - 2.1 m wide / 2 x 111 kW motors

     -    Coarse ore tripper conveyor - 2.1 m wide / 2 x 597 kW motors

     -    Coarse ore surge bins - 4 # sections 800 tonne capacity each - steel
          construction

     -    Coarse ore screens - 4# - Ludowici 3.5 x 8 m vibrating banana screens

     -    Secondary crushers - 4# - Metso MP1000 crushers / 750 kW drives

     -    Secondary crusher discharge conveyor - 1.8 m / 2 x 447 kW motors

     -    Secondary crusher product transfer conveyor - 2.1 m / 1 x 111 kW motor

     -    Coarse ore screen undersize conveyor - 1.8 m / 2 x 447 kW motors

     -    Coarse ore screen undersize transfer conveyor - 2.1 m / 1 x 111 kW
          motor

     -    HPGR surge bin feed conveyor - 2.1 m wide / 2 x 597 kW motors

     -    HPGR feed bins - 4# sections 1200 tonne capacity each - steel
          construction

     -    HPGR crusher feeders - 4# CEI 1.5 m wide belt feeders / 150 kW drives

     -    HPGR discharge conveyor - 2.1 m wide / 3 x 597 kW motors

     -    HPGR product conveyor - 2.1 m wide / 2 x 597 kW motors

     -    HPGR - 4# Polysius 2.4m x 1.7m 5000 kW


Area 3300 Grinding

Area 3300 includes ball mill feed surge bins from which ore is reclaimed by belt
feeders and transferred directly onto ball mill feed wet screens. Oversize
material from the screens is discharged onto a conveyor for recirculation to the
crushing HPGRs. Screen undersize is discharged directly to the ball mill cyclone
feed sumps. The four grinding lines each consist of dual screens, ball mill,
sump and cyclone feed pump, and a cyclone cluster. For each line, the ball mill
discharge and screen undersize product discharges to a single sump, from which
the single cyclone feed pump feeds to the cyclone cluster. The grinding circuit
facilities are installed within an open structure that supports service cranes
for the mills and cyclones.

Major equipment includes:

     -    Ball mill feed surge bins - 4# sections 5000 tonne capacity each -
          reinforced concrete construction

     -    Ball mill screen feeders - 4# CEI 2.1 m wide belt feeders / 261 kW
          drives

     -    Ball mill feed screens - 8# Ludowici 3 x 7.3 m double deck banana
          screens

     -    Ball mill screen oversize conveyor - 1.8 m wide / 1 x 597 kW motor


                                      A-3-7
<PAGE>
     -    Ball mills - 4# Polysius 7.3 m diameter x 10.7 m long shell supported
          mills with 12MW wrap around motors

     -    Primary cyclone feed pumps - 4# Krebs Millmax 28" x 26" pumps / 1120
          kW motors

     -    Primary cyclones - 4# Krebs cyclone clusters with 8 - 840 mm cyclones

Area 3400 Copper Flotation

Area 3400 includes rougher-scavenger flotation, regrind milling, and cleaner
flotation. The rougher-scavenger flotation circuit consists of four rows of 10
agitated flotation cells. Concentrate from the rougher-scavenger flotation cells
is split into two streams and treated separately in the regrind circuits before
being combined in the final cleaner circuit.

Major equipment includes:

     -    Rougher flotation cells - 4 rows of 10 Dorr-Oliver Eimco 160 m3 cells
          with 185 kW mechanisms

     -    Rougher concentrate polishing mills - 2 # Metso SMD-355 polishing
          mills with 355 kW drives

     -    Regrind mills - 3# Metso VTM 1500 vertical tower mills with 1118 kW
          drives

     -    Column cells - 4# MinnovEX 5 m x 12 m column cells

     -    Cleaner/Scavenger flotation cells - 1 row of 4 cleaner and 6 scavenger
          Dorr-Oliver Eimco 160 m3 cells with 185 kW mechanisms

Area 3500 Molydenum Plant

The molybdenum circuit processes the copper-molybdenum (Cu-Mo) bulk concentrate.
The bulk concentrate is treated through rougher/scavenger flotation cells and
cleaner flotation cells to produce final molybdenum concentrate. The tailing
from the Mo circuit is the final Cu concentrate and is transferred to the Cu
concentrate thickener. The Mo plant is located in an open outdoor structure with
a roof extending over the filter/dryer area.

Major equipment includes:

     -    Cu-Mo Concentrate thickener - Delkor 30 m diameter high rate thickener

     -    Mo rougher flotation cells - 4# Dorr-Oliver Eimco 30 m3 flotation
          cells with 55 kW mechanisms

     -    Mo rougher/scavenger flotation cells - 2# Dorr-Oliver Eimco 30 m3
          covered flotation cells with 55 kW mechanisms


                                      A-3-8
<PAGE>
     -    Mo 1st cleaner flotation cells - 7# 8.5 m3 Dorr-Oliver Eimco flotation
          cells with 22 kW mechanisms

     -    Mo cleaner scavenger flotation cells - 7# 4.2 m3 Dorr-Oliver Eimco
          flotation cells with 11 kW mechanisms

     -    Mo 1st cleaner concentrate thickener - Delkor 15 m diameter high rate
          thickener

     -    Mo cleaner column cells - 5# MinnovEX 1 m to 2.6 m diameter by 12 m
          column cells

     -    Mo concentrate filter - 1 # Larox 12.6 m2 filter

     -    Mo concentrate dryer - 1 # 19 m2 dryer

Area 3600 Concentrate Dewatering & Loadout

Mo scavenger flotation tailing is thickened in a 20 m diameter Cu concentrate
thickener and then transferred to 2 agitated storage tanks. The concentrate is
pumped from the tanks to one of two copper concentrate filters located in an
enclosed structure above a 3600 tonne capacity storage area. The concentrate is
transferred by a front-end loader onto a conveyor to load trucks for shipment
offsite.

Major equipment includes:

     -    Cu concentrate thickener - Delkor 20 m high rate thickener

     -    Cu concentrate storage tanks - 2# - 11 m dia. x 11 m high storage
          tanks with Lightnin 56 kW agitators

     -    Cu concentrate filters - 2# - Larox 144 m2 filters

Area 3700 Tailing Thickening

The tailing thickening circuit in the concentrator area consists of two 75 m
diameter high rate thickeners, thickener underflow pumps, thickener overflow
reclaim water tank, and associated pumps.

Major equipment includes:

Tailing thickeners - 2# 75m Dorr-Oliver Eimco thickeners complete with launders

Area 4000 - Tailing Storage Facility

The tailing storage facility consists of an earthen starter embankment that is
built up over time using sand from the hydro-cyclones processing the thickened
tailing. Fine tailing are deposited behind the tailing embankment. Supernatent
water from deposited tailing is recovered using 3 barges. The water is routed
using CS piping to the tailing cyclones and the Concentrator plant.


                                      A-3-9
<PAGE>
Major Equipment includes:

Cyclones - primary stage -Krebs 2 banks of 20-model gMax15-3264 with 18
installed, secondary stage Krebs 1 bank of 26-model gMax26-3137 with 14
installed

Barge Pumps - 5 off on 2 barges plus 2 on 1 barge (total 7) Goulds VIT-FF 24x28
GHXC-30BHC c/w 1300 HP motors

Reclaim Distribution system - 4 off Goulds VIC-T 12x14x16 GHXC-16GHC, 6 stage
vertical turbine pumps c/w 800 HP motors

Booster Pumps - 2 stations each with 4 off ITT-Goulds model 9800 20x16L-WSFH/6V
c/w 1200 HP motors

Seepage Reclaim - 3 off Goulds VIT-FF 8x16 BLC 14 stage vertical turbine c/w 800
HP motors


                                     A-3-10
<PAGE>
                                                                         Annex B
                                              to Physical Facilities Certificate

                               PHYSICAL FACILITIES
                                   DESCRIPTION

<TABLE>
<CAPTION>
       Facility or Equipment Required
by Appendix [__] of the Master Participation       Description of Facility or
            Agreement, as amended                 Equipment Actually Installed
--------------------------------------------   ---------------------------------
<S>                                            <C>

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------

--------------------------------------------   ---------------------------------
</TABLE>


                                     A-3-11
<PAGE>
                                                                         Annex C
                                              to Physical Facilities Certificate

                               CAPITAL SPARES AND
                            KEY CONSUMABLES INVENTORY

[this list will be defined from the purchase orders issued for the approximately
     $14 million of spares allowed for in the budget - this document will be
   prepared by the Borrower at the time of completion and will be reviewed for
                 its reasonableness by the Independent Engineer]

      ALL SPARES ARE TO BE OF EQUIVALENT QUALITY TO THE ITEMS THEY REPLACE.

CAPITAL SPARES AND KEY CONSUMABLE INVENTORY

I.   REQUIRED CAPITAL SPARES

A.   HGPR MECHANICAL SPARES

     [TBD]

B.   HPGR DRIVE SPARES MOTOR

     [TBD]

C.   MAIN TRANSFORMER

     [TBD]

D.   GYRATORY CRUSHER SPARES

     [TBD]

E.   COARSE ORE CONVEYOR SYSTEM SPARES

     [TBD]

F.   BALL MILL SPARES

     [TBD]

G.   REGRIND VERTIMILL SPARES

     [TBD]


                                     A-3-12
<PAGE>
H.   LIME VERTIMILL SPARES

     [TBD]

I.   THICKENER SPARES

     [TBD]

J.   CONCENTRATE SLURRY AGITATOR SPARES

     [TBD]

II.  REQUIRED CONSUMABLES INVENTORY

     [TBD]


                                     A-3-13
<PAGE>
                                                                         Annex D
                                              to Physical Facilities Certificate

                 DESCRIPTION OF INDEPENDENT ENGINEER PROCEDURES

                      [To be completed at time of delivery]


                                     A-3-14
<PAGE>
                                                                    Appendix A-4
                                                         To Completion Guarantee

                    FORM OF INSURANCE COMPLETION CERTIFICATE

     I, [NAME OF SENIOR OFFICER OF BORROWER], [TITLE OF SENIOR OFFICER] of
Borrower, hereby certify, as of the date hereof, that all insurance coverage
required to be in full force and effect after the Start-up of Commercial
Production pursuant to Section 8.01 of the Master Participation Agreement is in
full force and effect in all material respects.

     This is the certificate referred to in clause (d) of Section 2.01 of the
Completion Guarantee dated as of September 30, 2005, among the Parent Companies,
the Administrative Agent and the Senior Facility Lenders, as the same may be
amended from time to time (the "Completion Guarantee"). Capitalized terms used
herein, except as otherwise defined herein, shall have the meanings assigned to
them in the Completion Guarantee or, if not defined therein, the meanings
assigned to them in Schedule Z to the Master Security Agreement, dated as of
September 30, 2005, among the Borrower, the Senior Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers, the Administrative
Agent, the Trustee, the Offshore Collateral Agent and the Onshore Collateral
Agent, as the same may be amended from time to time (the "Master Security
Agreement").

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]


                                     A-4-1
<PAGE>
     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER OF BORROWER] have caused
this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF SENIOR OFFICER OF BORROWER]


                                        By
                                           -------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

     Aon Risk Services, Inc., a _____________ organized under the laws of
____________, hereby certifies that it concurs with the certification of the
Borrower set forth hereinabove as of the date hereof.

     IN WITNESS WHEREOF, Aon Risk Services, Inc. has caused this certificate to
be duly executed.

Dated:
       -------------

                                        AON RISK SERVICES, INC.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                     A-4-2
<PAGE>
                                                                    Appendix A-5
                                                         to Completion Guarantee

                      FORM OF LEGAL COMPLETION CERTIFICATE

     I, [NAME OF SENIOR OFFICER OF BORROWER], [TITLE OF SENIOR OFFICER] of the
Borrower, hereby certify that, as of the date hereof:

          (a) No MPA Default, MPA Event of Default, or Event of Political Force
     Majeure has occurred and is Continuing.

          (b) Each of the Project Documents and Security Documents is in full
     force and effect in all material respects or, in the case of Project
     Documents, has been replaced in accordance with the Master Participation
     Agreement with an agreement that is in full force and effect.

          (c) The Water License is in full force and effect in all material
     respects.

          (d) The security interests required under the Master Security
     Agreement and purported to be created by or pursuant to the Security
     Documents have been created and are perfected to the extent required under
     the Master Security Agreement and are in full force and effect in all
     material respects, subject to the qualifications and exceptions set forth
     in the opinion of Peruvian counsel to the Borrower delivered at Closing.

          (e) The Peruvian Governmental Approvals listed in Annex B have been
     obtained and are in full force and effect in all material respects.

          (f) All other material Peruvian Governmental Approvals, that are
     required as of the date hereof, for operation of the Sulfide Project and
     the Current Operations have been obtained and are in full force and effect
     in all material respects.

          (g) Each of the Offtake Agreements is in full force and effect.

          (h) Attached is a true and correct copy of a legal opinion of Rodrigo,
     Elias & Medrano, Abogados, Peruvian counsel to the Borrower,* substantially
     in

----------
*    This firm may be replaced by the Borrower with any other Peruvian counsel
     reasonably acceptable to the [Majority Facility Lenders].


                                     A-5-1
<PAGE>
     the form attached hereto as Annex A and addressed to the undersigned and
     the Senior Facility Lenders, which confirms the matters set forth in
     paragraphs (c), (d) and (e) above.

     This is the certificate referred to in clause (e) of Section 2.01 of the
Completion Guarantee dated as of September 30, 2005, among the Parent Companies,
the Administrative Agent and the Senior Facility Lenders, as the same may be
amended from time to time (the "Completion Guarantee"). Capitalized terms used
herein, except as otherwise defined herein, shall have the meanings assigned to
them in the Completion Guarantee or, if not defined therein, the meanings
assigned to them in Schedule Z to the Master Security Agreement, dated as of
September 30, 2005, among the Borrower, the Senior Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers, the Administrative
Agent, the Trustee, the Offshore Collateral Agent and the Onshore Collateral
Agent, as the same may be amended from time to time (the "Master Security
Agreement").

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]


                                     A-5-2
<PAGE>
     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER OF BORROWER] have caused
this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF SENIOR OFFICER OF BORROWER]


                                        By
                                           -------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                     A-5-3
<PAGE>
                                                                      Annex A to
                                                    Legal Completion Certificate

                              FORM OF LEGAL OPINION


                                     A-5-4
<PAGE>
                              Legal opinion of Rodrigo, Elias & Medrano Abogados
                                                  (Legal Completion Certificate)

Lima, __________

Sociedad Minera Cerro Verde S.A.A.
[Japan Bank for International Cooperation]
[KfW]
[CALYON New York Branch]
[The Royal Bank of Scotland plc]
[The Bank of Nova Scotia]
[Mizuho Corporate Bank, Ltd.]
[Sumitomo Mitsui Banking Corporation, as Lead JBIC Arranger]
[The Bank of Tokyo-Mitsubishi, Ltd., as Lead JBIC Arranger]
[Other Senior Facility Lenders]

Ladies and Gentlemen:

We have acted as special Peruvian counsel to Sociedad Minera Cerro Verde S.A.A.
(the "Borrower") in connection with the Master Participation Agreement, dated
__________, among the Borrower, the Senior Facility Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers and the Administrative
Agent.

Unless otherwise expressly provided herein, all capitalized terms used but not
defined herein shall have the respective meanings given to such terms in
Schedule Z to the Master Security Agreement referred to in Recital J of the
Master Participation Agreement. The term "Water License" shall mean [description
of the Water License]. The term "Security Agreements" shall mean, collectively,
the Mining Mortgage Agreement, dated __________, between the Borrower and the
Onshore Collateral Agent, [the Mortgage Agreement, dated __________, between the
Borrower and the Onshore Collateral Agent,](1) the Mining Pledge Agreement,
dated __________, between the Borrower and the Onshore Collateral Agent, the
Mining Floating Pledge Agreement, dated __________, between the Borrower and the
Onshore Collateral Agent, and the Share Pledge Agreement, dated __________,
among each of the Shareholders and the Onshore Collateral Agent. The term
"Opinion Peruvian

----------
(1)  Include only if required to be executed prior to rendering this opinion in
     accordance with the Master Participation Agreement.


                                     A-5-5
<PAGE>
Governmental Approvals" shall mean, collectively, the Peruvian Governmental
Approvals listed in Exhibit A.

This opinion is delivered at the request of the Borrower in order to be attached
by the Borrower to the Legal Completion Certificate referred to in Section
2.01(e) of the Completion Guarantee.

In rendering this opinion, we have reviewed copies of the Water License and the
Opinion Peruvian Governmental Approvals and assumed that, at the time of so
doing, the officials which executed the Water License and the Opinion Peruvian
Governmental Approvals were duly authorized and had the power and authority to
execute the Water License and the Opinion Peruvian Governmental Approvals on
behalf of the relevant Peruvian Governmental Authority.

In our examination, we have assumed the genuineness of all signatures, the
authenticity of all documents submitted to us as originals and the conformity
with authentic originals of all documents submitted to us as copies. In
addition, we have examined such corporate records, certificates and other
documents of the Borrower and such certificates of CAVALI ICLV S.A., and such
questions of law, as we have considered necessary or appropriate for the
purposes of this opinion.

Based upon and subject to the foregoing and subject also to the comments and
qualifications set forth below, we are of the opinion that:

1.   The Water License is in full force and effect in all material respects.

2.   The first priority Liens in favor of the Onshore Collateral Agent, for the
     benefit and on behalf of the Secured Parties, purported to be created by or
     pursuant to the Security Agreements are in full force and effect in all
     material respects.

3.   The Opinion Peruvian Governmental Approvals are in full force and effect in
     all material respects.

The foregoing opinions are limited to matters involving the laws of Peru and we
do not express any opinion as to the law of any other jurisdiction. Our opinions
set forth herein are based upon the facts in existence and laws in effect as of
the date hereof and we expressly disclaim any obligation to update our opinions
herein with respect to any changes in such facts or laws that may come to our
attention after delivery of this opinion.

We provide this opinion to you in our capacity as Peruvian counsel to the
Borrower and this opinion may not be relied for any purpose other than in


                                     A-5-6
<PAGE>
connection with the Legal Completion Certificate referred to in Section 2.01(e)
of the Completion Guarantee without, in each instance, our prior written
consent.

Very truly yours,


-------------------------------------


                                     A-5-7
<PAGE>
                                    Exhibit A

                 List of Opinion Peruvian Governmental Approvals

-    Third phase of the approval of the Beneficiation Concession expansion by
     the General Directorate of Mining of the Ministry of Energy and Mines;

-    Approval of the Mines Closure Plan for the Sulfide Project by the General
     Directorate of Mining Environmental Affairs of the Ministry of Energy and
     Mines;

-    Approval of the Environmental Impact Study for the 220 KV transmission line
     by the General Directorate of Environmental Affairs of the Ministry of
     Energy and Mines;

-    Approval of the concession for the 220 KV transmission line by the General
     Directorate of Electricity of the Ministry of Energy and Mines; and

-    Approval of the amendment to the Environmental Impact Study for the Sulfide
     Project regarding the bi-modal transport of concentrates to the Port of
     Matarani by the General Directorate of Mining Environmental Affairs of the
     Ministry of Energy and Mines and the Ministry of Transportation and
     Communications.


                                     A-5-8
<PAGE>
                                                                      Annex B to
                                                    Legal Completion Certificate

                PERUVIAN GOVERNMENTAL APPROVALS TO BE COVERED IN
                            COMPLETION LEGAL OPINION

-    Approval of the Closure Plan for the Mines and the Sulfide Project by the
     Ministry of Energy and Mines.

-    Approval of the Environmental Impact Study for the 220 KV line by the
     Ministry of Energy and Mines.

-    Approval by the Electrical Direction of the Ministry of Energy and Mines of
     the concession for the 220 KV Transmission Line.

-    Third phase of the approval of the beneficiation concession expansion and
     the construction permit to be granted after completion of the construction
     and inspection process.

-    Approval of an amendment to the Environmental Impact Study for the Sulfide
     Project regarding the bi-modal transport of concentrates to the Matarani
     port.


                                     A-5-9
<PAGE>
                                                                    Appendix A-6
                                                         to Completion Guarantee

                  FORM OF I.A. FINANCIAL COMPLETION CERTIFICATE

     We, [NAME OF INDEPENDENT PUBLIC ACCOUNTANTS], Independent Public
Accountants of the Borrower, hereby certify that, as of the month-end
immediately preceding the date hereof:

          (a) The credit balance of the Senior Debt Service Reserve Sub-Account
     is equivalent to or greater than fifty percent (50%) of the next succeeding
     Senior Debt Service Installment.

          (b) The Borrower does not have Working Capital Debt outstanding.

     This is the certificate referred to in clause (f) of Section 2.01 of the
Completion Guarantee dated as of September 30, 2005, among the Parent Companies,
the Administrative Agent and the Senior Facility Lenders, as the same may be
amended from time to time (the "Completion Guarantee"). Capitalized terms used
herein and in any annex hereto, except as otherwise defined herein, shall have
the meanings ascribed thereto in the Completion Guarantee or, if not defined
therein, the meanings ascribed to such terms in Schedule Z to the Master
Security Agreement among the Borrower, the Senior Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers, the Administrative
Agent, the Trustee, the Offshore Collateral Agent and the Onshore Collateral
Agent dated as of September 30, 2005, as the same may be amended from time to
time (the "Master Security Agreement").

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]


                                      A-6-1
<PAGE>
     IN WITNESS WHEREOF, we, [NAME OF INDEPENDENT PUBLIC ACCOUNTANTS], have
caused this certificate to be duly executed.

Dated:
       -------------
                                        [NAME OF INDEPENDENT PUBLIC ACCOUNTANTS]


                                        By
                                           -------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                     A-6-2
<PAGE>
                                                                    Appendix A-7
                                                         to Completion Guarantee

                FORM OF BORROWER FINANCIAL COMPLETION CERTIFICATE

     I, [NAME OF SENIOR OFFICER OF THE BORROWER], hereby certify that, as of the
month-end immediately preceding the date hereof:

     (a)  All undisputed amounts owing to Fluor Daniel Sucursal Del Peru and
          Fluor Canada Ltd. pursuant to the Construction Agreements have either
          been paid in full or have been fully reserved by the Borrower.

     This is the certificate referred to in clause (g) of Section 2.01 of the
Completion Guarantee dated as of September 30, 2005, among the Parent Companies,
the Administrative Agent and the Senior Facility Lenders, as the same may be
amended from time to time (the "Completion Guarantee"). Capitalized terms used
herein, except as otherwise defined herein, shall have the meanings assigned to
them in the Completion Guarantee or, if not defined therein, the meanings
assigned to them in Schedule Z to the Master Security Agreement, dated as of
September 30, 2005, among the Borrower, the Senior Lenders, the Lead JBIC
Arrangers, the Global Coordinators, the Lead Arrangers, the Administrative
Agent, the Trustee, the Offshore Collateral Agent and the Onshore Collateral
Agent, as may be amended from time to time (the "Master Security Agreement").

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]


                                     A-7-1
<PAGE>
     IN WITNESS WHEREOF, I, [NAME OF AUTHORIZED OFFICER OF BORROWER] have caused
this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF AUTHORIZED OFFICER OF BORROWER]


                                        By
                                           -------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                     A-7-2
<PAGE>
                                                                    Appendix A-8
                                                         to Completion Guarantee

                        FORM OF ENVIRONMENTAL CERTIFICATE

     I, [NAME OF SENIOR OFFICER], [TITLE OF SENIOR OFFICER] of the Borrower,
hereby attests that, as of the date hereof:

          (a) Construction of the Sulfide Project complies in all material
     respects with, and the Sulfide Project is being operated in all material
     respects in compliance with, the Environmental Guidelines.

          (b) Construction of the Sulfide Project and the operations and
     properties of the Borrower are in compliance with the JBIC Environmental
     Guidelines, except for any immaterial issues of non-compliance of which the
     Borrower is not specifically aware and as to which no remedial action has
     been requested by any applicable Governmental Authority.

          (c) The independent review board of the Sulfide Project has approved
     the Operational and Maintenance and Instrumentation Procedure Manuals for
     the Tailings Storage Facility, which plans were developed by the Borrower
     as required by Annex D (Application of the EA to Large Dams and Reservoirs)
     of Operational Policy 4.01 (Environmental Assessment).

          (d) The Closure Plan has been submitted in final form to all
     applicable Governmental Authorities and is in compliance with the
     Environmental Guidelines and all applicable Peruvian environmental laws,
     rules and regulations of the applicable Governmental Authorities, except
     where non-compliance is immaterial and all reasonable efforts are being
     made to promptly remedy such non-compliance.

          (e) Construction of the Sulfide Project conforms with, and the Sulfide
     Project is being operated in compliance with, all applicable Peruvian
     environmental laws, rules and regulations, except where non-compliance is
     immaterial and all reasonable efforts are being made to promptly remedy
     such non-compliance.

     This is the certificate referred to in paragraph (h) of Section 2.01 of the
Completion Guarantee dated as of September 30, 2005, among the Parent Companies,
the Administrative Agent and the Senior Facility Lenders, as the same may be
amended from time to time (the "Completion Guarantee"). Capitalized terms used
herein, except as otherwise defined in the Completion Guarantee, shall have the
meanings ascribed thereto


                                     A-8-1
<PAGE>
in Schedule Z to the Master Security Agreement among the Borrower, the Senior
Lenders, the Lead JBIC Arrangers, the Global Coordinators, the Lead Arrangers,
the Administrative Agent, the Trustee, the Offshore Collateral Agent and the
Onshore Collateral Agent dated as of September 30, 2005, as the same may be
amended from time to time (the "Master Security Agreement").


                                     A-8-2
<PAGE>
     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER], have caused this
certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title: Senior Officer


                                     A-8-3
<PAGE>
     We, [NAME OF INDEPENDENT ENGINEER] organized under the laws of
_____________ have performed such inspections, observations, analyses and other
procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex A to this certificate. Based
on such procedures, we hereby certify that we have no reason to believe that the
certifications of the Borrower set forth in paragraphs (a) and (b) above are not
true and correct in all material respects as of the date hereof.

     IN WITNESS WHEREOF, [NAME OF SENIOR OFFICER OF INDEPENDENT ENGINEER] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [Name of Independent Engineer]


                                        By:
                                            ------------------------------------
                                        [Name]
                                               ---------------------------------
                                        [Position]
                                                   -----------------------------


                                     A-8-4
<PAGE>
                                                                         Annex B
                                                                 To Appendix A-8

     "Environmental Guidelines": means to the extent applicable under the
Equator Principles (a) World Bank Environmental, Health and Safety Guidelines
(i) Mining and Milling - Open Pit dated August 11, 1995, (ii) Pollution
Abatement and Prevention Handbook 1998: General Environmental Guidelines, (iii)
Operational Policy 4.01 (Environmental Assessment), (iv) Operational Policy 4.04
(Natural Habitats), (v) Operational Policy 4.11 (Cultural Property), (vi) with
respect to the tailings dam, Operational Policy 4.37 (Dam Safety), and (vii)
Pollution Abatement and Prevention Handbook 1998: Part III Project Guidelines,
Monitoring, and Base Metal and Iron Ore Mining, each as in effect as of the date
of the Master Participation Agreement, and (b) IFC Safeguard Policies dated
September 1998 as in effect as of the date of the Master Participation
Agreement.
<PAGE>
                                                                    Appendix A-9
                                                         to Completion Guarantee

               FORM OF PRODUCTION CERTIFICATE - PARTIAL COMPLETION

          I, [NAME OF SENIOR OFFICER], [title of Senior Officer] of the
     Borrower, hereby certify that:

     (a) Attached to this certificate as Annex B are copies of operating
records, bills of lading and other data and documentation relating to production
by the Borrower during the periods referred to in clause (e) below. Such
documentation accurately reflects, in all material respects, the production of
the Borrower during the period to which it relates, and evidences compliance
with the certifications set forth in sections (i) through (vii) of clause (g)
below.

     (b) All sampling procedures relevant to the matters covered by this
certificate were conducted by the Borrower in accordance with standard
international mining practices; all assaying was conducted by the Borrower in
accordance with standard international mining practices. The sampling locations
and laboratory assay procedures have been verified by the Independent Engineer.

     (c) The Independent Engineer was provided with the Borrower's most recently
approved Three Year Budget Plan (the "Reference Budget Plan") that covers the
Completion Test Period, together with (i) the current block model and mine plan
(together, the "Current Mine Plan") related to the Reference Budget Plan and
(ii) the past 12 months' operating reports for the Borrower. The Reference
Budget Plan and the Current Mine Plan are in all material respects consistent
with, and contemplate life-of-loan operating and production results not
materially divergent from those projected in, the Primary Sulfide Mine Plan and
Project Financial Model (together, the "2005 Plan") on which the April 7, 2005
Information Memorandum delivered to the Senior Facility Lenders was based
(except for such material changes thereto, if any, as have been previously
furnished to the Senior Facility Lenders, reported on by the Independent
Engineer, and approved by the Majority Facility Lenders). [SELECT ONE: "The
foregoing certification can be made" OR "The foregoing certification cannot be
made. Accordingly, all subsequent references in this Certificate to "Reference
Budget Plan" and "Current Mine Plan" shall mean the 2005 Plan."]

     (d) The Reference Budget Plan was provided to the Independent Engineer at
least 30 Business Days' prior to the start of the Completion Test Period. Notice
of the start of the Completion Test Period was given to the Independent Engineer
at least 15 days prior to the start of such period. The Current Mine Plan was
substantially adhered to during the Completion Test Period.

     (e) The "Completion Test Period" began on [start date] and ended on [date],
and comprised at least 45 Operating Days falling outside of the traditional
"wet" months of January, February and March.

     (f) For purposes of this certificate,

          (i)  "Completion Test Period" is defined as a period of 90 Operating
               Days in any 100-day continuous period.
<PAGE>
          (ii) "Operating Day" is defined as any day other than a day on which
               (a) the operations of the Sulfide Project ceased for more than 12
               continuous hours due to force majeure or (b) work at the Sulfide
               Project was prohibited by applicable law or labor agreement.

          (iii) "force majeure" is defined as an act of God, labor dispute and
               industrial action of any kind (including, without limitation, a
               strike, interruption, slowdown and other similar action on the
               part of organized labor), a lockout, act of the public enemy, war
               (declared or undeclared), civil war, sabotage, blockade,
               revolution, riot, insurrection, civil disturbance, terrorism,
               epidemic, cyclone, tidal wave, landslide, lightning, earthquake,
               flood, storm, fire, adverse weather conditions, expropriation,
               nationalization, act of eminent domain, laws, rules, regulations
               or orders of governmental authority, acts of other private and
               public companies, explosion, breakage or accident to machinery or
               equipment or pipe or transmission line or other facility not of a
               systemic nature, embargo, inability to obtain or delay in
               obtaining equipment, materials, transport, event of political
               force majeure or any event whether similar to the foregoing or
               not which is not within the reasonable control of the Borrower,
               and which has a material adverse effect on the ability of the
               Borrower to perform its obligations, including, without
               limitation, such event which has a material adverse effect on the
               ability of the Borrower to mine, produce or ship copper
               concentrate.

     (g) COMPLETION TEST.

     During the Completion Test Period, the Borrower achieved the following
results of operations at the Sulfide Project and (in the case of items (iii) and
(vi) below) at its oxide processing and cathode production facilities:

     (i)  MINE TEST:

          -    Total mined tonnage (including to and from the ore stockpiles)
               during the Completion Test Period was at least 75% of the planned
               tonnage for such period as forecast in the Current Mine Plan.

     (ii) MILL TEST:

          -    The Borrower milled ore during the Completion Test Period at an
               average rate of at least 75% of 108,000 tons per day.

          -    The Borrower produced copper in concentrate during the Completion
               Test Period totaling at least 75% of planned tonnes of copper in
               concentrate as forecast in the Reference Budget Plan for such
               period.


                                      A-9-2
<PAGE>
          -    Copper concentrates produced during the Completion Test Period
               had an average copper grade at least equal to 90% of planned
               concentrate grade as forecast in the Reference Budget Plan for
               such period.

          -    Contained molybdenum recovered in molybdenum concentrate produced
               during the Completion Test Period was at least 50% of the planned
               recoverable molybdenum forecast in the Reference Budget Plan for
               such period.

          -    If the copper head grade during the Completion Test Period was
               more than 120% of the grade contemplated in the Reference Budget
               Plan for such period, then mill copper recovery was at least 90%
               of the recovery forecast in the Reference Budget Plan for such
               period (with Recovery = 100 x (C/H) x (H-T)/(C-T), where H, T, C
               are head, tail and concentrate % Cu).

     (iii) INFRASTRUCTURE TEST:

          -    Fresh Water Make-Up. The fresh water pumping system is capable of
               pumping at a rate at least 100% of the required make-up water
               defined in the water balance calculation based on the Borrower's
               actual operations and has pumped at a rate at least 90% of design
               capacity for at least one hour, and such capability and
               performance are demonstrated in the results (furnished to the
               Independent Engineer) of the mechanical completion test performed
               by Fluor and accepted by the Borrower under the Construction
               Agreements.

          -    Electrical Supply System. The new installed electrical supply
               system (substation, power line and power distribution system) has
               installed capacity to meet at least 90% of the design power
               requirements specified in the Fluor scope of work under the
               Construction Agreements which may be modified from time to time
               and which shall include the design power requirements specified
               in the Feasibility Study, and such capacity is demonstrated in
               the results (furnished to the Independent Engineer) of the
               mechanical completion test performed by Fluor and accepted by the
               Borrower under the Construction Agreements. During the Completion
               Test Period, 100% of the required power demand for the operation
               of the Primary Sulfide facilities was provided from the national
               power grid system.


                                      A-9-3
<PAGE>
     (iv) TAILING STORAGE:

          -    Viewed at the end of the Completion Test Period, the tailing
               production and hydro-cyclones system produced sufficient quantity
               and quality of sand material (at normal particle size) necessary
               to allow the dam embankment construction to contain the total
               volume of tailings produced to the end of the Completion Test
               Period (including the specified safety margin of freeboard as
               specified in the design parameters set forth in the Feasibility
               Study, as may be modified by the independent review board); and
               the to-date history of dam construction, at the beginning and at
               the end of the Completion Test Period, has been provided to the
               Independent Engineer to demonstrate the foregoing.

     (v)  SHIPPING AND QUALITY TESTS:

          -    90% of the copper concentrate tonnage produced during the
               Completion Test Period has been loaded onto ships for shipment
               (or alternatively loaded onto trucks for transport) to a
               processor during the 120-day period that includes the Completion
               Test Period.

          -    For all copper concentrate shipments for which settlement was
               made during the three-month period ending at the commencement of
               the Completion Test Period, total penalties (price reductions)
               assessable under applicable Sales Contracts did not exceed 5% of
               total sales price of such copper concentrate.

     (vi) CATHODE PRODUCTION:

          -    The Borrower produced cathodes during the six-month period ending
               at the end of the Completion Test Period totaling not less than
               90% of the total cathode production forecast in the Reference
               Budget Plan.

     (vii) EFFICIENCY TEST:

          -    The aggregate efficiency measure [(described in clause (c)(III)
               of the Efficiency Test description)] during the Completion Test
               Period did not exceed 115%.

This is the certificate referred to in paragraph (a) of Section 2.02 of the
Completion Guarantee, dated as of September 30, 2005, among the Parent
Companies, the Administrative Agent and the Senior Facility Lenders, as the same
may be amended from time to time (the "Completion Guarantee"). Capitalized terms
used herein, except as otherwise defined herein, shall have the meanings
assigned to them in the Completion Guarantee or, if not defined therein,
Schedule Z to the Master Security Agreement, dated as of September 30, 2005,
among the Borrower, the


                                      A-9-4
<PAGE>
Senior Lenders, the Lead JBIC Arrangers, the Global Coordinators, the Lead
Arrangers, the Administrative Agent, the Trustee, the Offshore Collateral Agent
and the Collateral Agent, as the same may be amended from time to time (the
"Master Security Agreement").

     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER], on behalf of the Borrower
have caused this certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                      A-9-5
<PAGE>
Annex A to

                             Production Certificate

     [NAME OF INDEPENDENT ENGINEER] a _______________ organized under the laws
of _____________ have performed such inspections, observations, analyses and
other procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex C to the Production
Certificate.

     Based on such procedures, we hereby certify that (1) we have no reason to
believe that any of the certifications of the Borrower set forth hereinabove is
not true and correct in all material respects as of the date hereof, (2) we
concur with the statement made in the second sentence of paragraph (c) of the
foregoing certificate and (3) in our professional opinion the operations of the
Borrower at the levels demonstrated during the Completion Test Period (as a
percentage of projected results in the Reference Budget Plan and Current Mine
Plan) are achievable and sustainable over the projected loan life as a technical
operating matter.

     IN WITNESS WHEREOF, [NAME OF SENIOR OFFICER OF INDEPENDENT ENGINEER] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF INDEPENDENT ENGINEER]


                                        BY:
                                            ------------------------------------
                                        [NAME]
                                               ---------------------------------
                                        [POSITION]
                                                   -----------------------------


                                      A-9-6
<PAGE>
                                   Annex B to
                             Production Certificate

[Attach copies of operating records, bills of lading and other data and
documentation relating to Sulfide Project and cathode production and operations
during relevant period, including data demonstrating compliance with the
certifications set forth in the Production Certificate.]


                                      A-9-7
<PAGE>
                                   Annex C to
                             Production Certificate

                 DESCRIPTION OF INDEPENDENT ENGINEER PROCEDURES

[To be completed at time of delivery]


                                      A-9-8
<PAGE>
                                                                   Appendix A-10
                                                         to Completion Guarantee

               FORM OF EFFICIENCY CERTIFICATE - PARTIAL COMPLETION

     I, [NAME OF SENIOR OFFICER], [title of Senior Officer] of the Borrower,
hereby certify that:

     (a) Attached to this certificate as Annex B are copies of operating records
and other data and documentation relating to production by and operation of the
Sulfide Project during the Completion Test Period referred to in clause (b)
below. Such documentation accurately reflects, in all material respects, the
production and operation of the Sulfide Project during the period to which it
relates, and evidences compliance with the certification set forth in clause
(c)(III) below.

     (b) (i) For purposes of this Certificate, the "Completion Test Period" is
the same as the Completion Test Period referred to in the Production Certificate
dated the date hereof provided by the Borrower to the Senior Facility Lenders
(the "Production Certificate").

          (ii) The forecast usage, forecast consumption and forecast
productivity figures set forth in each test below, identified in bold typeface,
are based on the 2005 Plan. If the Reference Budget Plan used for the Production
Certificate is different from the 2005 Plan but has been approved or certified
(by the Borrower and Independent Engineer) as contemplated in clause (c) and
Annex A of the Production Certificate, then such forecast figures will be
adjusted to reflect the differences, provided the Independent Engineer concurs
with such adjustments.

          (iii) If the actual average mine truck haulage distance during the
Completion Test Period varies from the forecast average distance by more than
10%, then, the forecast usage, forecast consumption and forecast productivity
figures set forth in each of clauses (A), (C), (D) and (E) of the mine test in
clause (c)(I) below, identified in bold typeface, will be adjusted by that
percentage difference.

     (c) EFFICIENCY TESTS

          (I)  MINE. The relevant percentages to be computed (based on actual
               performance during the Completion Period) and relative weightings
               are the following:

               (A)  FUEL:

                    Percentage: Average mining fleet diesel consumption per
                    operating hour during the Completion Test Period, in gallons
                    per operating truck hour, as a percentage of the forecast
                    consumption of 41.4 U.S. GAL./hr.

                    Weighting: 10.0%

               (B)  LOADING:

                    Percentage: Shovel operating hours to total tonnes of
                    material loaded on mine trucks during the Completion Test
                    Period as measured by the mine dispatch system, in mine
                    operating hours to


                                     A-10-1
<PAGE>
                    dry metric tonnes, as a percentage of the forecast ratio of
                    1 hr per 4,329 DMT.

                    Weighting: 6.0%

               (C)  HAULAGE:

                    Percentage: Truck operating hours to total tonnes of
                    material hauled from the mine and the ore stockpiles during
                    the Completion Test Period as measured by the mine dispatch
                    system, in mine operating hours to dry metric tonnes, as a
                    percentage of the forecast ratio of 1 hr per 548 DMT.

                    Weighting: 12.0%

               (D)  LABOR:

                    Percentage: Total mine workforce operating hours to tonnes
                    of material (including ore stockpiles) moved during the
                    Completion Test Period, in mine workforce operating hours to
                    dry metric tonnes, as a percentage of the forecast
                    productivity ratio of 1 hr per 99.5 DMT.

                    Weighting: 8.0%

               (E)  TIRES:

                    Percentage: Average mileage-life per mine truck tire (before
                    replacement), in total tires used to total miles of mine
                    truck haulage over the twelve-months period ending at the
                    end of the Completion Test Period, as a percentage of the
                    forecast rate of 1 tire per 64,000MI., provided that the
                    Independent Engineer may agree to a substantially equivalent
                    test.

                    Weighting: 4.0%

          (II) MILL. The relevant percentages to be computed (based on actual
               performance during the Completion Test Period) and relative
               weightings are the following:

               (A)  POWER:

                    Percentage: Average electricity consumption per tonne of ore
                    milled (including concentrator, water supply and water
                    return) during the Completion Test Period, in kilowatt hours
                    per dry metric tonne of ore milled, as a percentage of the
                    forecast rate of 22 KWH/dmt.


                                     A-10-2
<PAGE>
                    Weighting: 33.0%

               (B)  LABOR:

                    Percentage: Average daily total mill workforce to total
                    tonnes of ore milled during the Completion Test Period, in
                    size of workforce to dry metric tonnes of ore milled, as a
                    percentage of the forecast productivity ratio of 1 worker
                    per 341DMT.

                    Weighting: 12.0%

               (C)  WATER:

                    Percentage: Average liters of fresh water utilized per tonne
                    of ore milled during the Completion Test Period, in liters
                    per dry metric tonne of ore milled, as a percentage of the
                    forecast usage rate of 516 L/dmt.

                    Weighting: 6.0%

               (D)  LIME:

                    Percentage: Average kilograms of lime utilized per tonne of
                    ore milled during the Completion Test Period, in kilograms
                    per dry metric tonne of ore milled, as a percentage of the
                    forecast usage rate of 1.1 KG/dmt.

                    Weighting: 6.0%

               (E)  FLOCCULANT:

                    Percentage: Average grams of flocculant utilized per tonne
                    of ore milled during the Completion Test Period, in grams
                    per dry metric tonne of ore milled, as a percentage of the
                    forecast usage rate of 14 G/dmt.

                    Weighting: 3.0%

          (III) COMPOSITE TEST. Based on the actual performance of the Sulfide
               Project during the Completion Test Period, the weighted average
               of the percentages computed under clauses (A) through (E) of
               Section I and clauses (A) through (E) of Section II above,
               combined, did not exceed 115%.

This is the certificate referred to in paragraph (b) of Section 2.02 of the
Completion Guarantee, dated as of September 30, 2005, among the Parent
Companies, the Administrative Agent and the Senior Facility Lenders, as the same
may be amended from time to time (the "Completion Guarantee"). Capitalized terms
used herein, except as otherwise defined herein, shall have the


                                     A-10-3
<PAGE>
meanings assigned to them in the Completion Guarantee or, if not defined
therein, Schedule Z to the Master Security Agreement, dated as of September 30,
2005, among the Borrower, the Senior Lenders, the Lead JBIC Arrangers, the
Global Coordinators, the Lead Arrangers, the Administrative Agent, the Trustee,
the Offshore Collateral Agent and the Collateral Agent, as the same may be
amended from time to time (the "Master Security Agreement").

     IN WITNESS WHEREOF, I, [NAME OF SENIOR OFFICER], on behalf of the Borrower
have caused this certificate to be duly executed.

Dated:
       -------------

                                        SOCIEDAD MINERA CERRO VERDE S.A.A.


                                        By:
                                            ------------------------------------

                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                     A-10-4
<PAGE>
                                   Annex A to

                             Efficiency Certificate

     [NAME OF INDEPENDENT ENGINEER] a _______________ organized under the laws
of _____________ have performed such inspections, observations, analyses and
other procedures which we have, in our reasonable judgment, deemed necessary for
purposes of this certificate. Such procedures, and the names of our employees or
agents who performed them, are described in Annex C to this certificate.

     Based on such procedures, we hereby certify that (1) we have no reason to
believe that any of the certifications of the Borrower set forth hereinabove is
not true and correct in all material respects as of the date hereof, and (2) we
concur with the adjustments (if any) made to original forecasted figures in
accordance with paragraph (ii) and paragraph (iii) of clause (b) of the
foregoing certificate.

     IN WITNESS WHEREOF, [NAME OF SENIOR OFFICER OF INDEPENDENT ENGINEER] has
caused this certificate to be duly executed.

Dated:
       -------------

                                        [NAME OF INDEPENDENT ENGINEER]


                                        By:
                                            ------------------------------------

                                            ------------------------------------
                                        [Name]
                                               ---------------------------------
                                        [Position]
                                                   -----------------------------


                                     A-10-5
<PAGE>
                                   Annex B to

                             Efficiency Certificate

[Attach copies of operating records and other data and documentation relating to
Sulfide Project production and operations during relevant period, including data
demonstrating compliance with the certifications set forth in the Efficiency
Certificate.]


                                     A-10-6
<PAGE>
                                   Annex C to
                             Efficiency Certificate

                 DESCRIPTION OF INDEPENDENT ENGINEER PROCEDURES

                      [To be completed at time of delivery]


                                     A-10-7