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                                                               Exhibit 10.16

                                                               CONFORMED COPY


     FIRST SUPPLEMENTAL INDENTURE, dated as of November 12, 1996, to the
Indenture, dated as of September 20, 1996 (the "Indenture"), between
Commonwealth Aluminum Corporation, a Delaware corporation (the "Company"), each
of the Subsidiary Guarantors (as defined therein) and Harris Trust and Savings
Bank, as Trustee (the "Trustee").

     RECITALS:

     The original parties to the Indenture were the Company, the Trustee, and
Commonwealth Aluminum Lewisport, Inc., Commonwealth Aluminum Sales Corporation,
CALC Corporation, CasTech Aluminum Group Inc. and Barmet Aluminum Corporation as
Subsidiary Guarantors. Prior to the date hereof, CALC Corporation was merged
into CasTech Aluminum Group Inc. and CasTech Aluminum Group Inc. changed its
name to Alflex Corporation.

     The Company has duly organized Commonwealth Industries, Inc., a Delaware
corporation ("CII"), as a Restricted Subsidiary, and it is proposed that CII
become an additional Subsidiary Guarantor, as permitted by Section 901(7) of the
Indenture.

     The Company, each of the Subsidiary Guarantors and CII have been authorized
by Board Resolutions to enter into this supplemental indenture.

     NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

     For and in consideration of the premises it is mutually agreed, for the
equal and proportionate benefit of all Holders of the Securities, as follows:

                                   ARTICLE ONE

                                   Definitions


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     For all purposes of this supplemental indenture, unless the context
otherwise requires, the terms used herein shall have the same meanings as in the
Indenture.

                                   ARTICLE TWO

                              Subsidiary Guarantor

     CII is hereby subjected to the provisions (including the representations
and warranties) of the













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Indenture as a Subsidiary Guarantor, all as contemplated by Section 1303 of the
Indenture.

     IN WITNESS WHEREOF, the parties hereto have caused this supplemental
indenture to be duly executed, and their respective corporate seals to be
hereunto affixed and attested, all as of the day and year first above written.


                                       COMMONWEALTH ALUMINUM CORPORATION
                                       COMMONWEALTH ALUMINUM LEWISPORT, INC.
                                       COMMONWEALTH ALUMINUM SALES CORPORATION
                                       ALFLEX CORPORATION
                                       BARMET ALUMINUM CORPORATION
                                       COMMONWEALTH INDUSTRIES, INC.


                                       By /s/ Mark V. Kaminski
                                       ----------------------------
                                       Mark V. Kaminski, President


Attest:


/s/ D.L. Marsh Jr.
----------------------------
Executive Vice President & Secretary






                                       HARRIS TRUST AND SAVINGS BANK,
                                       as Trustee


                                       By /s/ J. Bartolini
                                       ----------------------------
                                       J. Bartolini, Vice President





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Attest:

Signature illegible
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COMMONWEALTH OF KENTUCKY)
                            ss.:
COUNTY OF JEFFERSON     )


     On the   22  day of November, 1996, before me personally came Mark V.
            -----
Kaminski, to me known, who, being by me duly sworn, did depose and say that he
is President of each of Commonwealth Aluminum Corporation, Commonwealth Aluminum
Lewisport, Inc., Commonwealth Aluminum Sales Corporation, Alflex Corporation,
Barmet Aluminum Corporation and Commonwealth Industries, Inc., corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporations; that the seals affixed to said instrument are such
corporate seals; that they were so affixed by authority of the Boards of
Directors of said corporations, and that he signed his name thereto by like
authority.

                                            /s/ Katherine M. Leonard
                                            ----------------------------

STATE OF ILLINOIS)
                     ss.:
COUNTY OF COOK   )


     On the   26th day of November, 1996, before me personally came
            ------

J. Bartolini          , to me known, who, being by me duly sworn, did depose and
----------------------
say that she is a           Vice President           of Harris Trust and Savings
                  ----------------------------------
Bank, one of the corporations described in and which executed the foregoing
instrument; that she knows the seal of said corporation; that the seal affixed
to said instrument is such corporate seal; that it was so affixed by authority
of the Board of Directors of said corporation, and that she signed her name
thereto by like authority.






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                                            /s/ Marianne Cody
                                            ----------------------------

























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