EXHIBIT 10.4 AMENDMENT TO RICHARDS BAY SLAG SALES AGREEMENT THIS AMENDING AGREEMENT dated May 1, 1999 is made by and between RICHARDS BAY IRON AND TITANIUM (PROPRIETARY) LIMITED, a South African corporation with offices at Richards Bay, Natal, South...

                                                                    EXHIBIT 10.4


                AMENDMENT TO XXXXXXXX BAY SLAG SALES AGREEMENT


THIS AMENDING  AGREEMENT  dated May 1, 1999 is made by and between  XXXXXXXX BAY
IRON AND  TITANIUM  (PROPRIETARY)  LIMITED,  a South  African  corporation  with
offices at Xxxxxxxx  Bay,  Natal,  South Africa  (hereafter  called  "RBIT") and
KRONOS INC., a Delaware  corporation with offices at X.X. Xxx 000, Xxxxxxxx Xxxx
Xxxx, Xxxxxxxxxx, Xxx Xxxxxx, 00000, XXX (hereafter called "Buyer").

WHEREAS,  RBIT and Buyer  entered into an agreement for the purchase and sale of
titanium  bearing  slag  produced at RBIT's plant at Xxxxxxxx  Bay,  Natal South
Africa  (hereafter  "RBIT  Product")  dated  as of the 1st day of May,  1995 and
amended as of November 3, 1997 (hereafter called the "Agreement");

WHEREAS,  the parties wish to amend the Agreement to provide for the extension
of the Term of the Agreement;

NOW THEREFORE,  for and in consideration of the covenants and conditions  herein
contained,  the parties hereto agree to amend the Agreement effective January 1,
1999 as follows:

1.    Article III shall be replaced with the following:

      This Agreement shall be in effect for a term of nine (9) years  commencing
      on January 1, 1995 up to and  including  December  31, 2003 (the  "Term"),
      subject to prior termination as hereinafter provided.

2.    The first sentence of Paragraph D of Article IV of the Agreement  shall be
      replaced by the following:

      [***]

3.    The last sentence of Paragraph D of Article IV of the  Agreement  shall be
      replaced with the following:

      [***]

4.    [***]

5.    Article V.A.3. shall be replaced with the following:

      "3.   For 1997 to 2003 inclusively,  the Basic Price of RB Slag shall be
            the  previous   year's  Basic  Price  plus  Escalation  as  herein
            defined."

[***] - Confidential treatment requested.


6.    The parties  hereby  ratify and confirm  the terms and  conditions  of the
      Agreement not specifically amended pursuant to this Amending Agreement.

IN WITNESS  WHEREOF,  the  parties  have caused this  Amending  Agreement  to be
executed by their duly authorized representatives.

XXXXXXXX BAY IRON AND TITANIUM                 KRONOS INC.
(PROPRIETARY) LIMITED


By:  /s/ X. X. Xxxxxx                          By:  /s/ X. X. Xxxxxx
Name:  X. X. Xxxxxx                            Name:  X. X. Xxxxxx
Title:  Managing Director                      Title:  V.P. Business Development















[***] - Confidential treatment requested.