Document:

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                                                                    EXHIBIT 4.12

                           NORD RESOURCES CORPORATION

                             3048 N. Seven Dash Road
                                  P.O. Box 384
                             Dragoon, Arizona 85609

                                                   Dated as of: November 8, 2004

Regiment Capital III, L.P.
222 Berkely Street, 12th Floor
Boston, Massachusetts 02116

Re: Amendment No. 1 to Post Closing Letter

Ladies and Gentlemen:

     We refer to that certain post-closing letter, dated October 19, 2004 (the
"Post-Closing Letter"), by Nord Resources Corporation, a Delaware corporation
(the "Borrower") and Regiment Capital III, L.P., a Delaware limited partnership
(the "Lender") delivered in connection with that certain Promissory Note, dated
October 19, 2004 (as amended, the "Note").

     Terms used in this Amendment No. 1 to the Post-Closing Letter (this
"Amendment") which are not defined herein, but which are defined in the Note,
shall have the same respective meanings herein as therein.

     We have requested you to make certain amendments to the Post-Closing
Letter. You have advised us that you are prepared and would be pleased to make
the amendments so requested by us on the condition that we join with you in this
Amendment.

     Accordingly, in consideration of these premises, the promises, mutual
covenants and agreements contained in this Amendment, and for other good and
valuable consideration, the receipt and sufficiency of all of which are hereby
acknowledged, the parties hereto, fully intending to be legally bound by this
Amendment, agree as follows:

     1. Effective as of November 18, 2004 (the "First Amendment Date"), the
     Post-Closing Letter is amended as follows:

          (a)  Paragraph 3 is hereby deleted and replaced in its entirety as
               follows:

               "Within ninety (90) days of the date hereof, the Borrower shall
               deliver to the Lender a deposit account control agreement for the
               Borrower's securities account held with A.G. Edwards; provided,
               however, that if as of such date there are no securities held in
               such account, and no purchases

<PAGE>

               of securities have been made from or through such account within
               sixty (60) days prior to such date, then the A.G. Edwards account
               may be closed and no Blocked Account Agreement shall be required
               with respect thereto."

     2. This Amendment has been duly executed and delivered to the Lender by the
     Borrower and is in full force and effect as of the date hereof, and the
     agreements and obligations of the Borrower contained herein constitute
     legal, valid and binding obligations of the Borrower enforceable against
     the Borrower in accordance with their respective terms.

     3. This Amendment may be executed in any number of counterparts, each of
     which when executed and delivered shall be deemed an original, but all of
     which together shall constitute one instrument. In making proof of this
     Amendment, it shall not be necessary to produce or account for more than
     one counterpart thereof signed by each of the parties hereto. Except to the
     extent specifically amended and supplemented hereby, all of the terms,
     conditions and the provisions of the Post-Closing Letter shall remain
     unmodified.

     If you are in agreement with the foregoing, please sign the form of
acceptance on the enclosed counterpart of the Amendment and return such
counterpart to the undersigned, whereupon this Amendment, as so accepted by you,
shall become a binding agreement between you and the undersigned.

                                         Very truly yours,

                                         NORD RESOURCES CORPORATION

                                         By: /s/ Erland Anderson
                                             -----------------------------------
                                         Name: Erland Anderson
                                               President

The foregoing Amendment is hereby accepted by the undersigned as of November 8,
2004.

REGIMENT CAPITAL III, L.P.

By: REGIMENT CAPITAL MANAGEMENT, LLC, as its General Partner

By: REGIMENT CAPITAL ADVISORS, LLC, as its Manager

By: /s/ Mark Brostowski
    ----------------------------------
Name: Mark Brostowski
      Vice President<PAGE>
                                                                    Exhibit 4.13

                                                                  ARIMETCO, INC.
                                                            8040 South Kolb Road
                                                                Tucson, AZ 85706
                                                        Telephone (520) 889-2040
                                                        Facsimile (520) 889-2733
                                                         E-mail: rshipes@msn.com

                                October 14, 2004

Nord Resources Corporation
3048 N. Seven Dash Rod., P.O. Box 384
Dragoon, AZ 85609

Dear Sir/Madam:

Nord Resources Corporation (the "Company") has advised Arimetco, Inc. (the
"Lender"), that it intends to pay off the obligations of the Company to the
Lender under that certain Promissory Note, in the aggregate principal amount of
$1,550,000.00, dated June 8, 1999 (as amended, supplemented or otherwise
modified prior to the date hereof, the "Note"). The amount required to payoff
the Lender (the "Pay Off Amount") as of October 14, 2004 (the "Pay Off Date") in
respect of all outstanding principal and accrued interest and fees owing by the
Company under the Note, is as follows:

<TABLE>
<S>              <C>
Principal        $602,382.43
Interest         $225,732.28
Fees             $         0
PAY OFF AMOUNT   $828,114.71
</TABLE>

Per diem interest continues to accrue on the Note at a rate of $180.95 per day.
This letter is issued on the understanding that the Company will not seek to
borrow any further amounts under the Note. Funds should be wired as follows:

          Name of Bank: Bank of America, NA
                        Midvale Park Branch
                        1601 W. Valencia
                        Tucson, AZ 85706

                        ABA No.: ABA 02600559593
                        Account No.: 004656445646
                        Attention:
                        Reference: Arimetco, Inc.
                        Contact:
                        Telephone No.: 520.295.5105

<PAGE>

                                      -2-

Upon receipt of the Pay Off Amount, together with a copy of this letter signed
by you, all obligations of the Company to the Lender shall have been satisfied
in full. Upon receipt of the Pay Off Amount, the Lender will release its
security interest and liens on the assets of the Company and provide you with
such UCC terminations, mortgage discharges or other release documents as you may
reasonably request.

Sincerely,

ARIMETCO, INC.

By: /s/ H.R. Shipes
    ---------------------------------
Name: H.R. Shipes
Title: President

ACCEPTED AND AGREED:

NORD RESOURCES CORPORATION

By: /s/ Erland Anderson
    ---------------------------------
Name: Erland Anderson
Title: President<PAGE>
                                                                    EXHIBIT 4.14

                       REVOLVING LINE OF CREDIT AGREEMENT

This Revolving Line of Credit Agreement (the "Agreement") is made and entered
into on this 21st day of June 2005, by and between Ronald A. Hirsch and Stephen
Seymour (individually, "Hirsch" or "Seymour" and collectively, "Lender"), and
Nord Resources Corporation, a Delaware corporation ("Borrower"). In
consideration of the mutual covenants and agreements contained herein, the
parties agree as follows:

1. LINE OF CREDIT. Lender hereby establishes for a period extending to December
31, 2005 (the "Maturity Date ") a revolving line of credit (the "Credit Line")
for Borrower in the principal amount of Six Hundred Thousand Dollars
($600,000.00) (the "Credit Limit"). In connection herewith, (i) Borrower shall
execute and deliver to Lender a secured promissory note (the "Secured Promissory
Note") in the amount of the Credit Limit and in form and content satisfactory to
Lender, and (ii) the parties shall execute a Security Agreement (the "Security
Agreement"). All sums advanced on the Credit Line or pursuant to the terms of
this Agreement (each an "Advance") shall become part of the principal of said
Secured Promissory Note.

2. ADVANCES. Any request for an Advance may be made from time to time and in
such amounts as Borrower may choose; provided, however, any requested Advance
will not, when added to the outstanding principal balance of all previous
Advances, exceed the Credit Limit. Requests for Advances may be made orally or
in writing by such officer of Borrower authorized by it to request such
Advances. Until such time as Lender may be notified otherwise, Borrower hereby
authorizes its president to request Advances. Lender may deposit or credit the
amount of any requested Advance to Borrower's checking account with Lender. In
Lender's sole discretion, Lender may refuse to make any requested Advance for
any reason or no reason at all. The funds from the Advances will be used by the
Borrower for operating expenses in connection with the operations of the
Borrower.

3. INTEREST. All sums advanced pursuant to this Agreement shall bear interest
from the date each Advance is made until paid in full at the rate of six percent
(6%) per annum, simple interest (the "Effective Rate"). The entire unpaid
principal balance, together with any accrued interest and other unpaid charges
or fees hereunder, shall be due and payable on the Maturity Date. All payments
shall be made to Lender at such place as Lender may, from time to time,
designate. All payments received hereunder shall be applied, first, to any costs
or expenses incurred by Lender in collecting such payment or to any other unpaid
charges or expenses due hereunder; second, to accrued interest; and third, to
principal. Borrower may prepay principal at any time without penalty.

4. SHARES AND WARRANTS. In consideration of Lender's extending the Credit Line
to Borrower, Borrower agrees to issue to Lender four shares of Lender's common
stock (the "Shares") and four warrants (the "Warrants," each such warrant a
"Warrant") for every One Dollar ($1.00) loaned to Borrower in Advances. Each
Warrant shall enable the Borrower to purchase one share of Lender's common stock
for an exercise price of twenty-five cents ($0.25) for three (3) years. The
Shares and

                                       -1-

<PAGE>

Warrants owed to Borrower for any particular Advance shall be issued in the
names of Hirsch and/or Seymour, in accordance to Borrower's instructions, within
ten (10) days of the Advance. Lender agrees that the Shares and Warrants shall
be "restricted securities" as defined by SEC Rule 144; however, Borrower agrees
to register for sale the Shares and the shares of common stock underlying the
Warrants on any registration statement that Borrower files during the next ten
(10) years with the Securities and Exchange Commission, except for any
registration statement filed on Form S-8.

5. REPRESENTATIONS AND WARRANTIES. In order to induce Lender to enter into this
Agreement and to make the advances provided for herein, Borrower represents and
warrants to Lender as follows:

     (a)  Borrower is a duly organized, validly existing, and in good standing
          under the laws of the State of Delaware with the power to own its
          assets and to transact business in Arizona, and in such other states
          where its business is conducted.

     (b)  Borrower has the authority and power to execute and deliver any
          document required hereunder and to perform any condition or obligation
          imposed under the terms of such documents.

     (c)  The execution, delivery and performance of this Agreement and each
          document incident hereto will not violate any provision of any
          applicable law, regulation, order, judgment, decree, article of
          incorporation, by-law, indenture, contract, agreement, or other
          undertaking to which Borrower is a party, or which purports to be
          binding on Borrower or its assets and will not result in the creation
          or imposition of a lien on any of its assets.

     (d)  Except as disclosed to Borrower, there is no action, suit,
          investigation, or proceeding pending or, to the knowledge of Borrower,
          threatened, against or affecting Borrower or any of its assets which,
          if adversely determined, would have a material adverse affect on the
          financial condition of Borrower or the operation of its business.

6. EVENTS OF DEFAULT. An event of default will occur if any of the following
events occurs:

     (a)  Failure to pay any principal or interest hereunder within ten (10)
          days after the same becomes due.

     (b)  Any representation or warranty made by Borrower in this Agreement or
          in connection with any borrowing or request for an Advance hereunder,
          or in any certificate, financial statement, or other statement
          furnished by Borrower to Lender is untrue in any material respect at
          the time when made.

                                       -2-

<PAGE>

     (c)  Default by Borrower in the observance or performance of any other
          covenant or agreement contained in this Agreement, other than a
          default constituting a separate and distinct event of default under
          this Paragraph 6.

     (d)  Filing by Borrower of a voluntary petition in bankruptcy seeking
          reorganization, arrangement or readjustment of debts, or any other
          relief under the Bankruptcy Code as amended or under any other
          insolvency act or law, state or federal, now or hereafter existing.

     (e)  Filing of an involuntary petition against Borrower in bankruptcy
          seeking reorganization, arrangement or readjustment of debts, or any
          other relief under the Bankruptcy Code as amended, or under any other
          insolvency act or law, state or federal, now or hereafter existing,
          and the continuance thereof for sixty (60) days undismissed, unbonded,
          or undischarged.

     (f)  Any material breach by Borrower of the terms of the Secured Promissory
          Note or the Security Agreement.

7. REMEDIES. Upon the occurrence of an event of default as defined above, Lender
may declare the entire unpaid principal balance, together with accrued interest
thereon, to be immediately due and payable without presentment, demand, protest,
or other notice of any kind. Lender may suspend or terminate any obligation it
may have hereunder to make additional Advances. To the extent permitted by law,
Borrower waives any rights to presentment, demand, protest, or notice of any
kind in connection with this Agreement. No failure or delay on the part of
Lender in exercising any right, power, or privilege hereunder will preclude any
other or further exercise thereof or the exercise of any other right, power, or
privilege. The rights and remedies provided herein are cumulative and not
exclusive of any other rights or remedies provided at law or in equity. Borrower
agrees to pay all costs of collection incurred by reason of the default,
including court costs and reasonable attorney's fees.

8. NOTICE. Any written notice will be deemed effective on the date such notice
is placed, first class, postage prepaid, in the United States mail, addressed to
the party to which notice is being given as follows:

Lender:   Ronald A. Hirsch
          668 North Coast Highway, #171
          Laguna Beach, CA 92651

          Stephen Seymour
          c/o Nord Resource Corporation
          3048 Seven Dash Road
          Dragoon, AZ 85609

Borrower: Nord Resources Corporation
          Attn.: Erland A. Anderson, President

                                       -3-

<PAGE>

          3048 Seven Dash Road
          Dragoon, AZ 85609

9. GENERAL PROVISIONS. All representations and warranties made in this Agreement
and the Secured Promissory Note and in any certificate delivered pursuant
thereto shall survive the execution and delivery of this Agreement and the
making of any loans hereunder. This Agreement will be binding upon and inure to
the benefit of Borrower and Lender, their respective successors and assigns,
except that Borrower may not assign or transfer its rights or delegate its
duties hereunder without the prior written consent of Lender. This Agreement,
the Secured Promissory Note, and all documents and instruments associated
herewith will be governed by and construed and interpreted in accordance with
the laws of the State of California. Time is of the essence hereof. This
Agreement will be deemed to express, embody, and supersede any previous
understanding, agreements, or commitments, whether written or oral, between the
parties with respect to the general subject matter hereof. This Agreement may
not be amended or modified except in writing signed by the parties.

EXECUTED on the day and year first written above.

The Borrower: NORD RESOURCES CORPORATION,
              A Delaware corporation

              /s/ Erland A. Anderson
              ---------------------------------
              By: Erland A. Anderson
              Its: President

The Lender:

              /s/ Ronald A. Hirsch
              ---------------------------------
              Ronald A. Hirsch, an individual

              /s/ Stephen Seymour
              ---------------------------------
              Stephen Seymour, an individual

                                       -4-

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