Exhibit 10.46

                               PURCHASE AGREEMENT

      This Purchase  Agreement (the  "Agreement") is made and entered into as of
the 20th day of November, 2002, by and between NL Industries, Inc., a New Jersey
corporation  ("NL"),  and the officer of NL listed on the signature  page hereto
(the "Seller").

                                    RECITALS

A.  Seller  holds  certain  options to  purchase  the number of shares of common
stock, par value $.125 per share (the "Common Stock"), of NL set forth under the
heading  "Number  of Options  Sold" on  Schedule  I to this  Agreement  (each an
"Option" and, collectively, the "Options").

B.  Seller  also holds  certain  shares of NL Common  Stock set forth  under the
heading  "Number of Shares Sold" on Schedule I to this  Agreement (the "Share"),
which Share were obtained upon exercise of certain stock options.

C.  Seller  proposed  to sell the  Options  and Shares to NL, and NL proposed to
purchase such Options and Shares, on the terms and subject to the conditions set
forth in this Agreement (the "Transaction").

      The parties hereto agree as follows:

                                   ARTICLE I.
                                 THE TRANSACTION

      Section 1.1.  Purchase and Sale of Shares and Options.  Against payment of
the purchase  price  therefor as specified in Section 1.2,  Seller hereby sells,
transfers,  assigns,  and delivered to NL the number of Shares under the heading
"Number of Shares Sold" on Schedule I hereto and the number of Options set forth
under the heading "Number of Options Sold" on Schedule I hereto.

      Section  1.2.  Delivery  of Shares and  Options.  In  connection  with the
purchase and sale of the Shares and Options,  Seller  hereby  agrees and directs
NL, and NL hereby agrees,  that no certificates  evidencing Shares acquired upon
exercise of options  shall be delivered to Seller,  and NL shall not be required
to issue any such Shares to Seller. Seller agrees that, promptly after execution
of this Agreement, the Options shall be cancelled.

      Section 1.3.  Purchase  Price and Payment.  NL hereby  purchases the Sales
from  Seller  for a  purchase  price in cash of $18.00  per  Share,  and  hereby
purchases  the Options  from  Seller for a purchase  price in cash of $18.00 per
Option, less the applicable exercise price of such Option. Seller agrees that NL
shall be entitled to deduct from the purchase price all  withholding  amounts NL
is required to pay in connection  with any exercise or sale of options by Seller
as set forth on Schedule I.


<PAGE>


                                 ARTICLE II.
                 REPRESENTATIONS AND WARRANTIES OF THE SELLER

      Seller  represents  and warrants to NL as of the date of this Agreement as
follows:

      Section  2.1.  Authority.  Seller is a natural  person  and has full legal
right,  power,  and  authority,  without  the  consent or  approval of any other
person,  to execute and deliver this  Agreement  and to perform his  obligations
hereunder.

      Section 2.2. Validity. This Agreement has been duly executed and delivered
by Seller and  constitutes a lawful,  valid,  and binding  obligation of Seller,
enforceable  against  Seller in  accordance  with its terms.  The  execution and
delivery of this Agreement and the  consummation of the Transaction by Seller do
not and will not violate or conflict  with any provision of, and do not and will
not result in a default  under (a) any material  contract,  agreement,  or other
instrument  to which  Seller is a party or by which  Seller  is  bound;  (b) any
order, writ,  injunction,  decree,  judgment of any court or governmental agency
applicable to Seller;  or (c) any law,  rule, or regulation  applicable to such,
except in each case for such violations,  conflicts,  or defaults that would not
have a material adverse consequence to the Transaction.

                                  ARTICLE III.
                      REPRESENTATIONS AND WARRANTIES OF NL

      NL  hereby  represents  and  warrants  to  Seller  as of the  date of this
Agreement as follows:

      Sections 3.1. Authority.  NL is a corporation validly existing and in good
standing under the laws of the State of New Jersey.  It has full corporate power
and authority,  without the consent or approval of any other person,  to execute
and  deliver  this  Agreement  and to perform  its  obligations  hereunder.  All
corporate  and  other  actions  required  to be taken by or on  behalf  of NL to
authorize the execution,  delivery,  and performance of this Agreement have been
duly and properly taken.

      Section 3.2. Validity. This Agreement has been duly executed and delivered
by NL and constitutes a lawful, valid, and binding obligation of NL, enforceable
against NL in  accordance  with its terms.  The  execution  and delivery of this
Agreement  and the  consummation  of the  Transaction  by NL do not and will not
violate or conflict  with any  provision of, and do not and will not result in a
default under (a) NL's charter or bylaws; (b) any material  contract,  agreement
or other  instruction  to which NL is a party or by which is it  bound;  (c) any
order, writ, injunction, decree, or judgment of any court or governmental agency
applicable to NL; or (d) any law,  rule, or regulation  applicable to NL, except
in each case for such violations,  conflicts,  or defaults that would not have a
material adverse consequence to the Transaction.

                                   ARTICLE IV.
                               GENERAL PROVISIONS

      Section 4.1.  Access to Information.  Seller has received all
information desired with respect to the business of NL.

<PAGE>

      Section 4.2.  Survival.  The  representations  and warranties set forth in
this   Agreement   shall  survive  the  execution  of  this  Agreement  and  the
consummation of the transactions contemplated herein.

      Section 4.3. Amendment and Waiver. No amendment or waiver of any provision
of this Agreement shall be effective  unless the same shall be in writing signed
by the party or parties against whom enforcement is sought.

      Section 4.4. Parties and Interest.  This Agreement shall bind and inure to
the benefit of the parties named herein and their respective heirs,  successors,
and assigns.

      Section  4.5.  Entire  Transaction.  This  Agreement  contains  the entire
understanding  among the parties with respect to the  transactions  contemplated
hereby and supersedes all other agreements and understandings  among the parties
with respect to the subject matter of this Agreement.

      Section  4.6.  Applicable  Law.  This  Agreement  shall be governed by and
construed in accordance  with the domestic  laws of the State of Texas,  without
giving effect to any choice of law or conflict of law provision or rule (whether
of  the  State  of  Texas  or any  other  jurisdiction)  that  would  cause  the
application of the laws of any jurisdiction other than the State of Texas.

      Section 4.7. Severability.  If any provision of this Agreement is found to
violate any statute,  regulation,  rule,  order,  or decree of any  governmental
authority,  court,  agency, or exchange,  such invalidity shall not be deemed to
affect any other  provision  hereof or the  validity  of the  remainder  of this
Agreement  and such  invalid  provision  shall be deemed  deleted to the minimum
extent necessary to cure such violation.

      Section  4.8.  Notice.   All  notices,   requests,   demands,   and  other
communications  hereunder shall be in writing and shall be sent by registered or
certified mail, postage prepaid,  as follows (or to such other address as Seller
or NL shall designate in writing):

            If to Seller:     c/o NL Industries, Inc.
                              16825 Northchase Drive, Suite 1200
                              Houston, Texas 77060

            If to NL:         NL Industries, Inc.
                              16825 Northchase Drive, Suite 1200
                              Houston, Texas 77060
                              Attention:  General Counsel

      Section 4.9.  Headings.  The sections and other headings contained in this
Agreement  are for  reference  purposes only and shall not affect in any way the
meaning or interpretation of this Agreement.
<PAGE>

      Section 4.10.  Expenses.  Except as otherwise  expressly  provided herein,
each of Seller and NL shall pay its own costs and  expenses in  connection  with
the transactions contemplated hereby.

      The parties  hereto have caused this  Agreement to be duly  executed as of
November 20, 2002.

                                     SELLER:



                                    /s/ J. Landis Martin
                                    --------------------
                                    J. Landis Martin






                                    NL INDUSTRIES, INC.



                              By:   /s/ Robert D. Hardy
                                    -------------------
                                    Robert D. Hardy
                                    Vice President



<PAGE>



                                   SCHEDULE I


Number of Shares Sold:         5,415
                          ---------------

                                           Exercise Price   Grant Date of Option

Number of Options Sold:       15,000       $14.25                   02/14/96
                          ---------------
                              15,000       $15.75                   02/14/96
                          ---------------
                              14,085       $11.875                  02/12/97
                          ---------------
                              30,000       $13.375                  02/12/97
                          ---------------
                              30,000       $14.875                  02/12/97
                          ---------------
                              19,800       $12.1875                 05/04/99
                          ---------------
                              19,800       $13.6875                 05/04/99
                          ---------------
                              19,800       $15.1875                 05/04/99
                          ---------------
                              40,000       $14.25                   02/09/00
                          ---------------


Amount of Withholding:      $301,826.00
                          ---------------