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                              LAFARGE CORPORATION
                             1993 STOCK OPTION PLAN

                   [AS AMENDED AND RESTATED FEBRUARY 7, 1995]

SECTION I.  PURPOSE

     The purpose of the Lafarge Corporation 1993 Stock Option Plan (the "Plan")
is to encourage and enable nonemployee directors of Lafarge Corporation (the
"Company") and key employees of the Company and its subsidiary corporations
("Subsidiary" or "Subsidiaries") as defined under Section 424(f) of the Internal
Revenue Code of 1986, as amended (the "Code"), upon whose judgment, initiative
and efforts the Company largely depends for the successful conduct of its
business, to remain with and devote their best efforts to the business of the
Company, thereby advancing the interests of the Company and its stockholders.
Accordingly, the Company may grant to certain employees the option to purchase
shares of the Common Stock of the Company, par value $1.00 per share ("Stock"),
and may award bonuses in the form of Stock subject to the restrictions set forth
in Section IX ("Restricted Stock"), as hereinafter set forth. Options to
purchase shares of Stock shall be granted automatically, as hereinafter set
forth, to members of the Board of Directors of the Company who are not officers
or employees of the Company or any Subsidiary ("Nonemployee Directors"). Options
granted to employees of the Company and its Subsidiaries and options granted to
Nonemployee Directors are referred to herein as "Employee Options" and "Director
Options", respectively, and collectively as "Options". Options granted under the
Plan shall be nonqualified stock options which shall not be treated as incentive
stock options under Section 422 of the Code.

SECTION II.  ADMINISTRATION OF THE PLAN

     The Plan shall be administered by a committee (the "Committee") of three or
more directors of the Company appointed by the Board of Directors. Members of
the Committee shall not, within one year prior to their appointment to the
Committee, have been granted or awarded equity securities pursuant to the Plan
(other than pursuant to Section X hereof) or pursuant to any other stock option
or stock plan of the Company or any parent or subsidiary corporation of the
Company (an "Affiliate") within the meaning of Section 424(e) and (f) of the
Code.

     The Committee shall have sole authority to determine the employees who are
to be granted Employee Options or stock appreciation rights or awarded
Restricted Stock from among those eligible hereunder and to establish the number
of shares of Stock to be optioned to each, the number of stock appreciation
rights to be granted to each, and the number of shares to be awarded to each in
the form of Restricted Stock after taking into consideration the position held,
the duties performed, the compensation received, the services expected to be
rendered by such employee and other relevant factors. The Committee is
authorized to interpret the Plan, and may from time to time adopt such rules and
regulations, not inconsistent with the provisions of the Plan, as it may deem
advisable to carry out the Plan; provided, however, that the Committee shall
have no authority, discretion or power to select the persons who will receive
Director Options, to set the number of shares to be covered by any Director
Option, to set the exercise price or the period within which Director Options
may be exercised or to alter any other terms or conditions specified herein,
except in the sense of administering the Plan subject to the express provisions
hereof. A majority of the Committee shall constitute a quorum and the acts of a
majority of the members present at any meeting at which a quorum is present, or
acts approved in writing by a majority of the Committee, shall be deemed the
acts of the Committee. All decisions made by the Committee in selecting the
employees to whom Employee Options and stock appreciation rights shall be
granted or Restricted Stock shall be awarded, in establishing the number of
shares which may be issued under each Employee Option or awarded as Restricted
Stock to employees and in construing the provisions of the Plan shall be final.
No member of the Committee shall be liable for any action taken, failure to act,

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determination or interpretation made in good faith with respect to the Plan or
any Option or stock appreciation right granted or Restricted Stock awarded under
the Plan.

SECTION III.  SHARES SUBJECT TO THE PLAN

     The aggregate number of shares of Stock issued under Options or awarded in
the form of Restricted Stock under this Plan shall not exceed 3,000,000 shares.
Such shares of Stock may consist of authorized but unissued shares of Stock or
previously issued shares of Stock reacquired by the Company. Any of such shares
of Stock which remain unissued and which are not subject to outstanding Options
and have not been awarded in the form of Restricted Stock at the termination of
the Plan shall cease to be subject to the Plan. Should any Option hereunder
expire or terminate prior to its exercise in full, or any Stock previously
awarded as Restricted Stock be forfeited, the shares of Stock subject to such
Option at the time of its expiration or termination and the shares of Restricted
Stock so forfeited will again be available for grant or award under the Plan.
The aggregate number of shares of Stock which may be issued under the Plan shall
be subject to adjustment as provided in Section XI hereof. Exercise of an Option
in any manner, including an exercise involving an election of an alternative
settlement method referred to in Section VII hereof, shall result in a decrease
in the number of shares of Stock which may thereafter be available for purposes
of the Plan by the number of shares of Stock as to which the Option is
exercised.

SECTION IV.  ELIGIBILITY

     The Committee shall determine and designate, at any time or from time to
time, the key employees of the Company and the Subsidiaries to whom Employee
Options are to be granted or Restricted Stock is to be awarded, but subject to
the terms and conditions set forth below:

          (a) The Committee may authorize the grant of Employee Options and the
     award of Restricted Stock only to individuals who are key employees
     (including officers and directors who are also key employees) of the
     Company or a Subsidiary at the time the Option is granted or the Restricted
     Stock is awarded. Options may be granted or Restricted Stock awarded to the
     same employee on more than one occasion.

          (b) The aggregate number of shares of Stock which may be issued under
     Employee Options granted or Restricted Stock awarded under the Plan to any
     one employee shall not exceed the lesser of 500,000 shares or 5% of the
     outstanding shares of Stock.

SECTION V.  OPTION PRICE

     The Option price per share of Stock underlying each Employee Option shall
be fixed by the Committee at the time the Option is granted, but shall not be
less than 100% of the fair market value of the Stock at the time of the granting
of the Option. The Option price per share of Stock underlying each Director
Option shall be 100% of the fair market value of the Stock at the time of the
granting of the Option. For purposes of the Plan, the fair market value of Stock
on any particular date shall be the mean of the high and low sales prices of
publicly traded shares of Stock on the date in question as reported on the
Composite Transactions reporting system or, if the Stock is listed on a U.S.
national securities exchange, the last sales price reported on such exchange on
that date, provided, that if there are no sales of Stock on the date in
question, then such determination shall be made on the basis of sales of Stock
on the last preceding date for which such sales are reported.

SECTION VI.  OPTION TERM

     The expiration date of an Employee Option shall be determined by the
Committee at the time of grant, but shall in no event be later than ten years
from the date of grant. The expiration date of each Director Option shall be the
date that is ten years from the date of grant.

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SECTION VII.  OPTION AGREEMENTS

     Each Option shall be evidenced by an option agreement ("Option Agreement")
and shall contain such terms and conditions not inconsistent with the provisions
of the Plan as may be approved by the Committee. The terms and conditions of the
respective Option Agreements evidencing Employee Options need not be identical
and may be amended by the Committee from time to time, subject to the provisions
of the Plan. The terms and conditions of the respective Option Agreements
evidencing Director Options shall be identical, to the extent practicable, and
may be amended by the Committee as necessary to ensure compliance with the
provisions of the Plan. Payment of the purchase price of any Option exercised
shall be made to the Company either (i) in cash (including check, bank draft or
money order) or (ii) by delivering shares of Stock already owned by the optionee
and which have been owned for at least six (6) months, duly endorsed for
transfer or (iii) a combination of such Stock and cash. The fair market value of
any Stock so delivered shall be determined on the same basis as provided in
Section V hereof. An Option Agreement evidencing an Employee Option may provide
for the surrender of the right to purchase shares of Stock under the Option in
return for a payment in cash or shares of Stock or a combination of cash and
shares of Stock equal to the excess of the fair market value of the shares of
Stock with respect to which the right to purchase is surrendered over the Option
price therefor, on such terms and conditions as the Committee in its sole
discretion may prescribe.

SECTION VIII.  EXERCISE OF EMPLOYEE OPTIONS

     (a) Each Employee Option granted under the Plan shall be exercisable during
such period commencing on or after the expiration of one year from the date of
the grant of such Option as the Committee shall determine; provided, however,
that the otherwise unexpired portion of any Employee Option shall expire and
become null and void no later than upon the first to occur of (i) the expiration
of ten years from the date such Option was granted, (ii) the expiration of three
months from the date of the termination of the optionee's employment with the
Company or an Affiliate for any reason other than death, disability or
retirement under the normal or early retirement provisions of a pension or
retirement plan maintained by the Company or an Affiliate, or (iii) the
expiration of three years from the date of the termination of the optionee's
employment with the Company or an Affiliate by reason of death, disability or
retirement under the normal or early retirement provisions of a pension or
retirement plan maintained by the Company or an Affiliate. Transfer of
employment without interruption of service between or among the Company and its
Affiliates shall not be considered to be a termination of employment for the
purposes of this Plan. Any provision of this Plan to the contrary
notwithstanding, the otherwise unexpired portion of any Employee Option granted
hereunder shall expire and become null and void immediately upon an optionee's
termination of employment with the Company or an Affiliate by reason of such
optionee's fraud, dishonesty or performance of other acts detrimental to the
Company or an Affiliate.

     (b) Each Employee Option granted hereunder shall be exercisable in full or
in such annual installments as may be determined by the Committee at the time of
the grant; provided, however, that the Committee in its discretion may
subsequently accelerate the exercise date of an Employee Option. The right to
purchase shares of Stock shall be cumulative so that when the right to purchase
any shares of Stock has accrued, such shares or any part thereof may be
purchased at any time thereafter until the expiration or termination of the
Employee Option.

     (c) If the Committee grants stock appreciation rights in connection with an
Employee Option, either at the time of grant or by amendment, such rights shall
be subject to the same terms and conditions as the related Option and shall be
exercisable only to the extent the Option is exercisable. Stock appreciation
rights shall be granted only in connection with an Employee Option. A right
shall entitle the optionee to surrender to the Committee the related unexercised
Option, or any portion thereof, and to receive from the Company in exchange
therefor cash, shares of Stock, or a combination of cash and Stock, having an
aggregate value equal to (i) the excess of the fair market value of one share of
Stock over the Option price, times (ii) the number of shares of Stock called for
by the Option, or portion thereof, which is surrendered. The number of shares of
Stock which may be received pursuant to the exercise of a right may not exceed
the number of shares of Stock called for by the Option, or portion thereof,
which is surrendered. No fractional shares of Stock will be issued. The
Committee shall have the right to determine whether the Company's obligation
shall be paid in cash,
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shares of Stock, or a combination of cash and Stock. The Committee may establish
a maximum appreciation value which would be awardable under any granted right or
rights.

     (d) No Employee Option or stock appreciation right granted under the Plan
shall be transferable by the holder thereof otherwise than by will or by the
laws of descent and distribution, and shall be exercisable during the lifetime
of the optionee only by him or her.

     (e) Nothing in this Section shall operate to extend the period of exercise
of an Employee Option beyond the expiration date specified in the Option
Agreement.

SECTION IX.  RESTRICTED STOCK

     The Committee may from time to time, in its sole discretion, award bonuses
in the form of Restricted Stock to persons eligible to receive awards of
Restricted Stock under Section IV. All Restricted Stock awarded under the Plan
shall be subject to such restrictions, terms and conditions, if any, as may be
determined by the Committee. The Committee may in its sole discretion remove,
modify or accelerate the release of restrictions on any Restricted Stock in the
event of death or disability of the recipient of such Restricted Stock, or for
such other reasons as the Committee may deem appropriate. Nonemployee Directors
shall not be eligible to receive awards of Restricted Stock under this Plan.

     Any certificate or certificates representing shares of Restricted Stock
shall bear a stamped or printed notice on the face thereof to the effect that
such shares have been awarded pursuant to the terms of the Plan and may not be
sold, pledged, transferred, assigned or otherwise encumbered in any manner
except as set forth in the terms of such award. If the Committee so determines,
the certificates representing Restricted Stock shall be deposited by the
recipient with the Company or an escrow agent designated by the Company until
the restrictions thereon have lapsed or have been removed in accordance with the
provisions of this Section. Upon the lapse of the restrictions or removal
thereof by the Committee, new unrestricted certificates for the number of shares
on which the restrictions have lapsed or been removed shall, upon request by the
recipient of the Restricted Stock, be issued in exchange for such restricted
certificates.

SECTION X.  DIRECTOR OPTIONS

     In addition to the other provisions of this Plan relating to Director
Options, the following provisions shall govern the grant and exercise of
Director Options under the Plan:

     (a) Director Options shall be granted to Nonemployee Directors in
accordance with the following, provided, however, that a Nonemployee Director
may decline to accept any Director Option by giving notice to such effect to the
Committee or by refusing to execute an Option Agreement relating to the Option:

          (1) a Director Option representing the right to purchase 5,000 shares
     of Stock shall be granted effective as of the date of the meeting of the
     Committee held in February 1995 to each person serving as a Nonemployee
     Director on such date;

          (2) a Director Option representing the right to purchase 5,000 shares
     of Stock shall be granted automatically to each Nonemployee Director who
     was not granted a Director Option under subsection (a)(1), on and effective
     as of the date on which such person is first elected or appointed to serve
     as a Nonemployee Director, provided, that if a Nonemployee Director who has
     received a Director Option under subsection (a)(1) or (a)(2) of this
     Section X ceases serving as a director and is subsequently elected or
     appointed as a Nonemployee Director, he or she shall not receive a second
     Director Option pursuant to this subsection (a)(2); and

          (3) a Director Option representing the right to purchase 1,000 shares
     of Stock shall be granted automatically on and effective as of the date of
     the first meeting of the Committee in each year, beginning with the year
     1996, to each person who is a Nonemployee Director of the Company on such
     date (including persons who have previously received Director Options under
     this Plan);

provided, however, that if as of the effective date of any grant of Director
Options there are not sufficient shares available under the Plan to allow for
the grant to each Nonemployee Director of a Director Option for

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the number of shares provided herein, then each Nonemployee Director shall be
granted an option for a pro rata portion of the total number of shares then
available (disregarding fractional shares).

     (b) Each Director Option shall vest in accordance with the following:

          (1) one-fourth of the shares subject to the Director Option shall be
     vested at the date of grant of the Director Option for each continuous full
     year of service by the grantee on the Board of Directors of the Company
     prior to such date of grant; and

          (2) if the Director Option is not fully vested on the date of grant,
     one-fourth of the Shares subject thereto shall vest on each anniversary of
     the date of commencement of the grantee's service on the Board of Directors
     of the Company until the Director Option is fully vested, provided,
     however, that no portion of any Director Option shall vest after the
     Nonemployee Director's service on the Board of Directors has terminated for
     any reason.

Each Director Option shall be exercisable in whole at any time and in part from
time to time to the extent such Director Option has vested in accordance with
the foregoing; provided, however, that the otherwise unexpired portion of any
Director Option shall expire and become null and void no later than upon the
first to occur of (i) the expiration of ten years from the date such option was
granted, (ii) the expiration of three months from the date of the termination of
the Nonemployee Director's service on the Board of Directors of the Company for
any reason other than death or retirement under the normal or early retirement
provisions of any retirement plan maintained by the Company for Nonemployee
Directors or (iii) the expiration of three years from the date of the
termination of the Nonemployee Director's service on the Board of Directors of
the Company by reason of death or retirement under the normal or early
retirement provisions of any retirement plan maintained by the Company for
Nonemployee Directors. Any provision of this Plan to the contrary
notwithstanding, the otherwise unexpired portion of any Director Option granted
hereunder shall expire and become null and void immediately upon termination of
the Nonemployee Director's service on the Board of Directors if such termination
occurs by reason of such Nonemployee Director's (i) fraud or intentional
misrepresentation or (ii) embezzlement, misappropriation or conversion of assets
or opportunities of the Company or any Affiliate. The right to purchase shares
of Stock shall be cumulative so that when the right to purchase any shares of
Stock has accrued, such shares or any part thereof may be purchased at any time
thereafter until the expiration or termination of the Director Option.

     (c) Stock appreciation rights shall not be granted in connection with
Director Options.

     (d) No Director Option granted under the Plan shall be transferrable by the
holder thereof otherwise than by will or by the laws of descent and
distribution, and shall be exercisable during the lifetime of the optionee only
by him or her.

     (e) The aggregate number of shares of Stock which may be issued under
Director Options granted under the Plan to any one Nonemployee Director shall
not exceed the lesser of 20,000 shares or 5% of the outstanding shares of Stock.

     (f) Nothing in this Section shall operate to extend the period of exercise
of a Director Option beyond the expiration date specified in the Option
Agreement.

SECTION XI.  ADJUSTMENTS UPON RECAPITALIZATION OR REORGANIZATION

     In the event the Company shall effect a split of the Stock or dividend
payable in Stock (other than pursuant to the Company's Optional Stock Dividend
Plan), or in the event the outstanding Stock shall be combined into a smaller
number of shares, the maximum number of shares of Stock as to which Options may
be granted and Restricted Stock may be awarded under the Plan shall be increased
or decreased proportionately. In the event that before delivery by the Company
of all of the shares of Stock in respect of which any Option or stock
appreciation right has been granted under the Plan, the Company shall have
effected such a split, dividend or combination, the shares of Stock still
subject to the Option or stock appreciation right shall be increased or
decreased proportionately and the purchase price per share of Stock shall be
decreased or

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increased proportionately so that the aggregate purchase price for all of the
then optioned shares of Stock shall remain the same as immediately prior to such
split, dividend or combination.

     In the event of a reclassification of the Stock not covered by the
foregoing, or in the event of a liquidation or reorganization, including a
merger, consolidation or sale of assets, the Board of Directors shall make such
adjustments, if any, as it may deem appropriate in the number and kind of shares
for which Options, stock appreciation rights or Restricted Stock may be granted
or awarded under the Plan and, with respect to outstanding Options and stock
appreciation rights, in the number, purchase price and kind of shares covered
thereby. The provisions of this Section shall only be applicable if, and only to
the extent that, the application thereof does not conflict with any valid
governmental statute, regulation or rule.

SECTION XII.  CONTINUANCE OF EMPLOYMENT OR BOARD MEMBERSHIP

     Neither the Plan nor any agreement relating to any Option, stock
appreciation right or award of Restricted Stock shall impose any obligation on
the Company or an Affiliate to continue to employ any employee or to permit any
Nonemployee Director to continue as a director of the Company.

SECTION XIII.  WITHHOLDING

     The Company shall have the right to withhold taxes, as required by law,
from any transfer of cash or Stock to an employee under the Plan or to collect,
as a condition of such transfer, any taxes required by law to be withheld.

     (a) Subject to the provisions of paragraphs (b) and (c) of this Section, at
any time when an employee is required to pay to the Company an amount required
to be withheld under applicable tax laws in connection with an issuance of Stock
upon exercise of an Employee Option or stock appreciation right, the employee
may satisfy this obligation in whole or in part by electing (the "Election") to
have the Company withhold from the issuance shares of Stock having a fair market
value equal to the amount required to be withheld. The value of the shares of
Stock to be withheld shall be based on the fair market value of such shares as
of the date on which shares of Stock are issued to the employee pursuant to
exercise of the Option or stock appreciation right (the "Tax Date"). The
employee must pay to the Company any difference between the amount required to
be withheld by the Company and the value of the shares of Stock so withheld. Any
shares of Stock withheld shall not thereafter be available to be subject to an
Option granted under the Plan.

     (b) Each Election must be made prior to the Tax Date. The Committee may
disapprove of any Election, may suspend or terminate the right to make Elections
and may provide with respect to any Employee Option or stock appreciation right
that the right to make Elections shall not apply to such Option or stock
appreciation right. An Election is irrevocable.

     (c) If an employee is an officer or director of the Company within the
meaning of Section 16 of the Securities Exchange Act of 1934 and the rules and
regulations promulgated thereunder, then an Election is subject to the following
additional conditions:

          (1) No Election shall be effective with respect to a Tax Date which
     occurs within six months of the grant of the Option or stock appreciation
     right, except that this limitation shall not apply in the event the death
     or disability of the employee occurs prior to expiration of the six-month
     period.

          (2) The Election must be made either six months prior to the Tax Date
     or during a period beginning on the third business day following the date
     of release for publication of the Company's quarterly or annual summary
     statements of sales and earnings and ending on the twelfth business day
     following such date.

SECTION XIV.  AMENDMENT OR TERMINATION OF THE PLAN

     The Board of Directors in its discretion may terminate the Plan at any time
with respect to any shares of Stock for which Options have not theretofore been
granted or which have not been awarded as Restricted Stock. The Board of
Directors shall have the right to alter or amend the Plan or any part thereof
from time to

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time; provided, that no such change may be made which would impair the rights of
the optionee under any outstanding Option or the recipient of Restricted Stock
without the consent of such optionee or recipient; and provided, further, that
the Board of Directors may not make any alteration or amendment which would
materially increase the benefits accruing to participants under the Plan,
increase the aggregate number of shares of Stock which may be issued pursuant to
the provisions of the Plan, or materially modify the requirements for
participation in the Plan without the approval of the stockholders of the
Company. Notwithstanding the foregoing provisions of this Section XIV, the
provisions of the Plan governing (a) the number of Director Options to be
awarded to Nonemployee Directors, (b) the number of shares of Stock to be
covered by each such Director Option, (c) the exercise price per share under
each Director Option, (d) when and under what circumstances Director Options
will be granted and (e) the period within which Director Options may be
exercised, shall not be amended or altered more than once every six months,
other than to comport with changes in the Code or the rules promulgated
thereunder.

SECTION XV.  EFFECTIVENESS AND EXPIRATION OF THE PLAN

     If adopted by the Board of Directors and approved by the vote of the
holders of a majority of the stock of the Company entitled to vote thereon at a
meeting of stockholders duly called and held for such purpose, or at an annual
meeting thereof, the notice of which has specified that action is to be taken on
the Plan, and the Committee shall have been advised by legal counsel for the
Company that in the opinion of such counsel all applicable requirements of law
precedent to its becoming effective have been fully met, then the Plan shall
become effective on August 4, 1993 or as soon thereafter as the aforesaid
requirements have been met. The Plan shall expire five years after the effective
date of the Plan. If the stockholders of the Company fail so to approve the
Plan, the Plan shall thereupon terminate and all Options previously granted and
all awards of Restricted Stock under the Plan shall become void and of no
effect. The provisions of the Plan relating to Director Options shall become
effective as of the date of the meeting of the Committee held in February 1995
if such provisions are adopted by the Board of Directors and approved by the
stockholders of the Company in the manner specified in the first sentence of
this Section XV. If the stockholders of the Company fail so to approve such
provisions, such provisions and all conforming and other amendments to the Plan
adopted by the Board of Directors in connection therewith shall thereupon
terminate and all Director Options previously granted under the Plan, as amended
thereby, shall become void and of no effect. With respect to persons subject to
Section 16 of the Securities Exchange Act of 1934 (the "1934 Act"), transactions
under the Plan are intended to comply with applicable conditions of Rule 16b-3
or its successors under the 1934 Act. To the extent any provisions of the Plan
or action by the Committee fails to so comply, it shall be deemed null and void,
to the extent permitted by law and deemed advisable by the Committee or by the
Board of Directors.

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