Document:

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                                                                     EXHIBIT 4.3

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR
ANY STATE SECURITIES LAWS. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR
HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF A REGISTRATION STATEMENT
IN EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN OPINION OF COUNSEL
SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED OR UNLESS
SOLD PURSUANT TO RULE 144 OF SUCH ACT. ANY SUCH TRANSFER MAY ALSO BE SUBJECT TO
APPLICABLE STATE SECURITIES LAWS.

                          BOSTON LIFE SCIENCES, INC.

                     Warrant for the Purchase of Shares of
                     -------------------------------------
                                 Common Stock
                                 ------------

No.  BLSI - [INSERT NUMBER]                      [INSERT NUMBER] Shares

FOR VALUE RECEIVED, BOSTON LIFE SCIENCES, INC., A Delaware corporation (the
"Company"), hereby certifies that [INSERT NAME] or its permitted assigns, is
entitled to purchase from the Company, at any time or from time to time,
commencing on [INSERT DATE] (the "Initial Exercise Date"). This Warrant shall
expire at 5:00 P. M., New York City time, on [INSERT DATE], and is exercisable
for [INSERT NUMBER] fully paid and non-assessable shares of the Common Stock,
$.01 par value per share, of the Company for an aggregate purchase price of
[INSERT PRICE] computed on the basis of [INSERT PRICE] per share. (Hereinafter,
(i) said Common Stock, together with any other equity securities which may be
issued by the Company with respect thereto or in substitution therefor, is
referred to as the "Common Stock", (ii) the shares of the Common Stock
purchasable hereunder or under any other Warrant (as hereinafter defined) are
referred to as the "Warrant Shares", (iii) the aggregate purchase price payable
for the Warrant Shares hereunder is referred to as the "Aggregate Warrant
Price", (iv) the price payable for each of the Warrant Shares hereunder is
referred to as the "Per Share Warrant Price", (v) this Warrant, all similar
Warrants issued on the date hereof and all warrants hereafter issued in exchange
or substitution for this Warrant or such similar Warrants are referred to as the
"Warrants" and (vi) the holder of this Warrant is referred to as the "Holder"
and the holder of this Warrant and all other Warrants or Warrant Shares issued
upon the exercise of any Warrant are referred to as the "Holders"). The
Aggregate Warrant Price is not subject to adjustment. The Per Share Warrant
Price is subject to adjustment as hereinafter provided; in the event of any such
adjustment, the number of Warrant Shares shall be adjusted by dividing the
Aggregate Warrant Price by the Per Share Warrant Price in effect immediately
after such adjustment.
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     1.   Exercise of Warrant
          -------------------

          (a)    This Warrant may be exercised, in whole at any time or in part
from time to time, commencing on the Initial Exercise Date and prior to 5:00 P.
M. New York City time, on the Termination Date by the holder by the surrender of
this Warrant (with the subscription form at the end hereof duly executed) at the
address set forth in Subsection 9(a) hereof, together with proper payment of the
Aggregate Warrant Price, or the proportionate part thereof if this Warrant is
exercised in part, with payment for Warrant Shares made by certified or official
bank check payable to the order of the Company.

          (b)    If this Warrant is exercised in part, this Warrant must be
exercised for a number of whole shares of the Common Stock and the Holder is
entitled to receive a new Warrant covering the Warrant Shares which have not
been exercised and setting forth the proportionate part of the Aggregate Warrant
Price applicable to such Warrant Shares.  Upon surrender of this Warrant, the
Company will (i) issue a certificate or certificates in the name of the Holder
for the largest number of whole shares of the Common Stock to which the Holder
shall be entitled and, if this Warrant is exercised in whole, in lieu of any
fractional share of the Common Stock to which the Holder shall be entitled, pay
to the Holder cash in an amount equal to the fair value of such fractional share
(determined in such reasonable manner as the Company shall determine), and (ii)
deliver the other securities and properties receivable upon the exercise of this
Warrant, if any, or the proportionate part thereof if this Warrant is exercised
in part, pursuant to the provisions of this Warrant.

     2.   Reservation of Warrant Shares; Listing.  The Company agrees that,
          --------------------------------------
prior to the expiration of this Warrant, the Company will at all times (a) have
authorized and in reserve, and will keep available, solely for issuance or
delivery upon the exercise of this Warrant, the shares of the Common Stock and
other securities and properties as from time to time shall be receivable upon
the exercise of this Warrant, free and clear of all restrictions on sale or
transfer, except for the restrictions on sale or transfer set forth in the
Securities Act of 1933, as amended (the "Act"), and restrictions created by or
on behalf of the Holder, and free and clear of all preemptive rights and rights
of first refusal; and (b) if the Company prepares and files a registration
statement covering the shares of Common Stock issued or issuable upon exercise
of this Warrant with the Securities and Exchange Commission (the "SEC") which
registration statement is declared effective by the SEC under the Act and the
Company lists its Common Stock on any national securities exchange, it will use
its best efforts to cause the shares of Common Stock subject to this Warrant to
be listed on such exchange.

     3.   Protection Against Dilution.
          ---------------------------

          (a)    In case the Company shall hereafter (i) pay a dividend or make
a distribution on its capital stock in shares of Common Stock, (ii) subdivide
its outstanding shares of Common Stock into a great number of shares, (iii)
combine its outstanding shares of Common Stock into a smaller number of shares
or (iv) issue by reclassification of its Common Stock any shares of capital
stock of the Company, the Per Share Warrant Price shall be adjusted to be equal
to a fraction, the numerator of which shall be the Aggregate Warrant Price and
the denominator of which shall be the number of shares of Common Stock or other
capital stock of the Company which he would have owned immediately following
such action had such Warrant been exercised immediately prior thereto. An
adjustment made pursuant to this Subsection shall become effective immediately
after the record date in the case of a dividend or distribution and shall become
effective immediately after the effective date in the case of a subdivision,
combination or reclassification.

                                       2
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          (b)    No adjustment in the Per Share Warrant Price shall be required
in the case of the issuance by the Company of (a) Common Stock pursuant to the
exercise of any Warrant, (b) options or warrants to purchase Common Stock
(including the exercise thereof) issued or sold to employees, officers or
directors of or consultants and advisers to the Company or any subsidiary
thereof, and (c) shares of Common Stock issued or sold pursuant to stock
purchase or stock option plans or other similar arrangements that are approved
by the Company's Board of Directors.

          (c)    In case of any capital reorganization or reclassification, or
any consolidation or merger to which the Company is a party other than a merger
or consolidation in which the Company is the continuing corporation, or in case
of any sale or conveyance to another entity of the property of the Company as an
entirety or substantially as an entirety, or in the case of any statutory
exchange of securities with another corporation (including any exchange effected
in connection with a merger of a third corporation into the Company), the Holder
of this Warrant shall have the right thereafter to receive on the exercise of
this Warrant the kind and amount of securities, cash or other property which the
Holder would have owned or have been entitled to receive immediately after such
reorganization, reclassification, consolidation, merger, statutory exchange,
sale or conveyance had this Warrant been exercised immediately prior to the
effective date of such reorganization, reclassification, consolidation, merger,
statutory exchange, sale or conveyance and in any such case, if necessary,
appropriate adjustment shall be made in the application of the provisions set
forth in this Section 3 with respect to the rights and interests thereafter of
the Holder of this Warrant to the end that the provisions set forth in this
Section 3 shall thereafter correspondingly be made applicable, as nearly as may
reasonably be, in relation to any shares or other securities or property
thereafter deliverable on the exercise of this Warrant. The above provisions of
this Subsection shall similarly apply to successive reorganizations,
reclassifications, consolidations, mergers, statutory exchanges, sales or
conveyances. The issuer of any shares of stock or other securities or property
thereafter deliverable on the exercise of this Warrant shall be responsible for
all of the agreements and obligations of the Company hereunder. Notice of any
such reorganization, reclassification, consolidation, merger, statutory
exchange, sale or conveyance and of said provisions so proposed to be made,
shall be mailed to the Holders of the Warrants not less than 30 days prior to
such event. A sale of all or substantially all of the assets of the Company for
a consideration consisting primarily of securities shall be deemed a
consolidation or merger for the foregoing purposes.

          (d)    No adjustment in the Per Share Warranty Price shall be required
unless such adjustment would require an increase or decrease of at least $0.05
per share of Common Stock; provided, however, that any adjustments which by
                           --------  -------
reason of this Subsection are not required to be made shall be carried forward
and taken into account in any subsequent adjustment; provided, further, however,
                                                     -------- --------
that adjustments shall be required and made in accordance with the provisions of
this Section 3 (other than this Subsection) not later than such times as may be
required in order to preserve the tax-free nature of a distribution to the
Holder of this Warrant or Common Stock issuable upon the exercise hereof.  All
calculations under this section 3 shall be made to the nearest cent or to the
nearest 1/100th of share, as the case may be.  Anything in this Section 3 to the
contrary notwithstanding, the Company shall be entitled to make such reductions
in the Per Share Warrant Price, in addition to those required by this Section 3,
as it in its discretion shall deem to be advisable in order that any stock
dividend, subdivision of shares or distribution of rights to purchase stock or
securities convertible or exchangeable for stock hereafter made by the Company
to its stockholders shall not be taxable.

          (e)    If the Board of Directors of the Company shall declare any
dividend or other distribution with respect to the Common Stock other than a
cash distribution out of earned surplus, the Company shall mail notice thereof
to the Holders of the Warrants not less than 15

                                       3
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days prior to the record date fixed for determining stockholders entitled to
participate in such dividend or other distribution.

          (f)    If, as a result of an adjustment made pursuant to this Section
3, the Holder of any Warrant thereafter surrendered for exercise shall become
entitled to receive shares of two or more classes of capital stock or shares of
Common Stock and other capital stock of the Company, the Board of Directors
(whose determination shall be conclusive and shall be described in a written
notice to the Holder of any Warrant promptly after such adjustment) shall
determine the allocation of the adjusted Per Share Warrant Price between or
among shares or such classes of capital stock or shares of Common Stock and
other capital stock.

     4.   Fully Paid Stock; Taxes.  The Company agrees that the shares of the
          -----------------------
Common Stock represented by each and every certificate of Warrant Shares
delivered on the exercise of this Warrant be validly issued and outstanding,
fully paid and nonassessable, and not subject to preemptive rights or rights of
first refusal, and the Company will take all such actions as may be necessary to
assure that the par value or stated value, if any, per share of the Common Stock
is at all times equal to or less than the then Per Share Warrant Price.  The
Company further covenants and agrees that it will pay, when due and payable, any
and all Federal and State stamp, original issue or similar taxes which may be
payable in respect of the issue of any Warrant Share or any certificate thereof.

     5.   Limited Transferability.  This Warrant may not be sold, transferred,
          ------------------------
assigned or hypothecated by the Holder (a) except in compliance with the
provisions of the Act and the applicable state securities "blue sky" laws, or
(b) in the case of an individual, pursuant to such individual's last will and
testament or the laws of descent and distribution, and is so transferable only
upon the books of the Company which it shall cause to be maintained for such
purpose.  The Company may treat the registered Holder of this Warrant as he or
it appears on the Company's books at any time as the Holder for all purposes.
All warrants issued upon the transfer or assignment of this Warrant will be
dated the same date as this Warrant, and all rights of the holder thereof shall
be identical to those of the Holder.

     6.   Loss, Etc., of Warrant.  Upon receipt of evidence satisfactory to the
          ----------------------
Company of the loss, theft, destruction or mutilation of this Warrant, and of
indemnity reasonably satisfactory to the Company, if lost, stolen or destroyed,
and upon surrender and cancellation of this Warrant, if mutilated, the Company
shall execute and deliver to the Holder a new Warrant of like date, tenor and
denomination.

     7.   Warrant Holder Not Shareholder.  Except as otherwise provided herein,
          ------------------------------
this Warrant does not confer upon the Holder any right to vote or to consent to
or receive notice as a stockholder of the Company, as such, in respect of any
matters whatsoever, or any other rights or liabilities as a stockholder, prior
to the exercise hereof.

     8.   Communication.  No notice or other communication under this Warrant
          -------------
shall be effective unless in writing; such notice shall be deemed given on the
same day if sent by hand;

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after three (3) business days (Saturdays, Sundays and a bank or other public
holidays excluded) if sent by certified mail, return receipt requested; after
one day if sent by reputable overnight courier service; and if sent by telex
upon receipt of the answer back signal; or if by facsimile upon receipt of the
confirmation slip showing completion of the transmission, addressed as follows:

          (a)    The Company at 137 Newbury Street, 8/th/ Floor, Boston, MA
02116 or other address as the Company has designated in writing to the Holder,
or

          (b)    the Holder [INSERT ADDRESS] or other such address as the Holder
has designated in writing to the Company.

     9.   Headings. The headings of this Warrant have been inserted as a matter
          --------
of convenience and shall not affect the construction hereof.

     10.  Applicable Law.  This Warrant shall be governed by and construed in
          --------------
accordance with the law of the State of Delaware without giving effect to the
principles of conflicts of law thereof.

IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
President and attested to by its Secretary.

                                         BOSTON LIFE SCIENCES, INC.

                                         By:_______________________
                                             President

ATTEST:

_______________________
   Secretary

                                       5
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                                  SUBSCRIPTION
                                  ------------

          The undersigned, _______________________, pursuant to the provisions
of the foregoing Warrant, hereby agrees to Subscribe for and purchase
________________ shares of the Common Stock, par value $.01 per share, of Boston
Life Sciences, Inc. covered by said Warrant, and makes payment therefor in full
at the price per share provided by said Warrant.

Dated:__________________                     Signature:_________________________

                                             Address:___________________________

                                                     ___________________________

                                  ASSIGNMENT
                                  ----------

          FOR VALUE RECEIVED______________ hereby sells, assigns and transfers
unto ______________________the foregoing Warrant and all right evidenced
thereby, and does irrevocably constitute and appoint __________________________,
attorney, to transfer said Warrant on the books of Boston Life Sciences, Inc.

Dated:__________________                     Signature:_________________________

                                             Address:___________________________

                                                     ___________________________

                              PARTIAL ASSIGNMENT
                              ------------------

          FOR VALUE RECEIVED __________________ hereby assigns and transfers
unto ________________________ the right to purchase ___________ shares of the
Common Stock, par value $.01 per share, of Boston Life Sciences, Inc. covered by
the foregoing Warrant, and a proportionate part of said Warrant and the rights
evidenced thereby, and does irrevocably constitute  and appoint
____________________________, attorney, to transfer that part of said Warrant on
the books of Boston Life Sciences, Inc.

Dated:__________________                     Signature:_________________________

                                             Address:___________________________

                                                     ___________________________

                                       6SHARE PURCHASE AND SALE AGREEMENT

THIS AGREEMENT made effective the 13th day of January, 2000.

BETWEEN:  VEGA-ATLANTIC CORPORATION, a body corporate incorporated under the
          laws of the State of Colorado and carrying on business in the United
          States of America

          (the "Purchaser")

AND:      GOLDEN THUNDER RESOURCES LTD., a body corporate incorporated under the
          laws of British Columbia, and carrying on business in the City of
          Vancouver, British Columbia

          (the "Vendor")

AND:      TUN RESOURCES INC., a body corporate incorporated under the laws of
          British Columbia and carrying on business in the City of Vancouver,
          British Columbia and in the People's Republic of China.

          ("Tun Resources")

WHEREAS the Vendor is the registered and beneficial owner of all of the issued
and outstanding common shares in the capital stock of Tun Resources (the "Tun
Resources Shares"); and

WHEREAS the Vendor wishes to sell, transfer and convey the Tun Resources Shares
to the Purchaser and the Purchaser is offering to purchase 80% of the Tun
Resources Shares with an option to purchase the remaining 20% of the Tun
Resources Shares at a later date, subject to the terms and conditions contained
herein;

NOW THEREFORE THIS AGREEMENT WITNESSES that in consideration of the mutual
covenants, agreements, representations and warranties contained herein and other
good and valuable consideration (the receipt and sufficiency of which is hereby
acknowledged) the parties covenant and agree as follows:

1.   INTERPRETATION

1.1  Where used herein, the following terms shall have the following meanings:

     (a)  "Agreement", "hereto", "hereof", "herein", "hereby", and "hereunder"
          and similar expressions mean and refer to this Agreement as the same
          may be amended, modified or supplemented at any time or from time to
          time;

     (b)  "Assets" means the right, title and interest of Tun Resources in, to
          and under the Joint Venture and the Joint Venture Agreement;

<PAGE>

     (c)  "BCSC" means the British Columbia Securities Commission;

     (d)  "CDNX" means the Canadian Venture Exchange;

     (e)  "Closing" means the completion of the purchase and sale of the Tun
          Resources Shares pursuant hereto which shall take place within ten
          (10) business days of the acceptance of this Agreement for filing with
          the CDNX and the granting of shareholder approval of the Vendor to
          this Agreement, or on such other date as may be orally agreed between
          the parties hereto;

     (f)  "Joint Ventures" means that sino-foreign joint ventures created by the
          Joint Venture Agreements as more particularly described in Schedule
          "A" hereto;

     (g)  "Joint Venture Agreements" means those sino-foreign joint venture
          contracts entered into between Tun Resources, as more particularly
          described in Schedule "A" hereto, which create the Joint Ventures;

     (h)  "Purchase Price" means the purchase price set out in paragraph 2.1
          hereof;

     (i)  "The Purchaser Shares" means shares in the capital stock of the
          Purchaser issued to the Vendor as consideration for the purchase of
          the Tun Resources Shares; and

     (j)  "Vendor's Counsel" means Maitland & Company, Barristers and
          Solicitors, of Vancouver, British Columbia in their capacity as
          counsel to the Vendor.

2.   PURCHASE OF SHARES AND GRANT OF OPTION

2.1  Subject to Closing, as of the Closing the Vendor hereby sells, assigns,
     transfers and conveys to the Purchaser, and the Purchaser hereby purchases
     from the Vendor, 80% of the Tun Resources Shares in consideration of the
     issuance to the Vendor of 1,600,000 Rule 144 common shares in the capital
     stock of the Purchaser on Closing.

2.2  The Purchaser agrees, in partial consideration for the transfer of 80% of
     the the Tun Resources Shares to the Purchaser on Closing, to provide
     funding (by way of intercorporate loan) to Tun Resources US$1,180,000 on or
     before August 15, 2000 (the "Completion Date").

     (the "Capital Contributions")

2.3  The Vendor and the Purchaser agree that, as of the date of the execution of
     this Agreement (being May 1, 2000) US$140,000 of the Capital Contributions
     have been made by the Purchaser to Tun Resources. All funds advanced by the
     Purchaser to the Vendor or Tun Resources to this date are agreed to be
     Capital Contributions and shall be accounted for as such advances by the
     Purchaser.

2.4  In the event that the Capital Contributions are not made by the Purchaser
     on or before August 15, 2000, beneficial right, title and interest in and
     to the 80% of the Tun Resources Shares transferred to the Purchaser on
     Closing shall revert to the Vendor and the Purchaser agrees to make any and
     all reasonable efforts and undertake all reasonably necessary acts to
     assign, transfer or otherwise convey to the Vendor beneficial right, title
     and interest in and to these shares. The 80% of the Tun Resources Shares
     transferred to the Purchaser on Closing will be held in trust by an escrow
     agreement pending the completion of the Capital Contributions on the terms
     and conditions of an escrow agreement agreed to by the Purchaser and the
     Vendor.

<PAGE>

2.5  The Vendor hereby grants to, and the Purchaser hereby accepts, an option
     (the "Option") to purchase (until August 15, 2002 unless this Agreement is
     terminated by the failure of the Purchaser to make the Capital
     Contributions in 2.2 above) beneficial right, title and interest in and to
     the remaining 20% of the Tun Resources Shares (the "Option Shares") on the
     following terms and conditions:

     (a)  should the Purchaser wish to exercise the Option, it shall so notify
          the Vendor in writing;

     (b)  upon receipt of the notice in writing, the Purchaser and the Vendor
          (sharing the cost equally) shall have the Option Shares independently
          valued by a valuation expert acceptable to both of them;

     (c)  upon completion of the valuation in 2.5(b) above, the Purchaser shall,
          as the exercise price of the Option, pay to the Vendor the fair market
          value (valuation) of the Option Shares, in cash.

3.   REPRESENTATIONS AND WARRANTIES OF THE VENDOR

3.1  The Vendor hereby represents and warrants to and in favour of the Purchaser
     (the Purchaser relying on such representations and warranties in entering
     into this Agreement) that, as of the date hereof and as at the Closing:

     (a)  the Vendor is the registered owner of all of the issued and
          outstanding shares in the capital stock of Tun Resources and the
          Vendor has a 100% beneficial right, title and interest in and to these
          Tun Resources Shares;

     (b)  the Tun Resources Shares will be validly issued and outstanding as
          fully paid and non-assessable with no options, contracts, calls,
          commitments or rights of any character relating thereto;

     (c)  the Vendor has the full capacity and authority to sell, transfer,
          convey, assign or option its Tun Resources Shares in accordance with
          the terms of this Agreement;

     (d)  this Agreement and all other documents executed and delivered by the
          Vendor pursuant hereto constitute legal, valid and binding obligations
          of the Vendor enforceable in accordance with their terms;

     (e)  the Vendor's legal and beneficial title to its Tun Resources Shares is
          free and clear of all liens, charges, encumbrances, adverse claims and
          demands by any parties other than those to this Agreement;

     (f)  the Vendor is not a party to any actions, suits or other legal,
          administrative or arbitration proceedings or government investigations
          which might reasonably be expected to result in impairment or loss of
          the Vendors' interest in the Tun Resources Shares;

<PAGE>

     (g)  the entering into of this Agreement by the Vendor and the completion
          of sale by the Vendor of the Tun Resources Shares pursuant hereto will
          not, to the best of its knowledge, result in the violation of any law,
          regulation or statute of the Province of British Columbia or the
          People's Republic of China;

     (h)  the Vendor has incurred no obligations or liabilities, contingent or
          otherwise, for brokers' or finders' fees in respect of this
          transaction for which the Purchaser shall have any obligation or
          liability;

     (i)  Tun Resources is a private company duly incorporated, properly
          organized, validly existing and qualified to carry on business under
          the laws of the Province of British Columbia and has all necessary
          power, authority and capacity to own or otherwise hold its property
          and assets, is in good standing, and has conducted its business in
          accordance with applicable laws;

     (j)  there will be no outstanding shareholders' loans owing to the Vendor
          by Tun Resources;

     (k)  Tun Resources holds no assets other than the Assets;

     (l)  other than the Joint Venture Agreements and the Joint Ventures, Tun
          Resources does not own any shares in any corporations or any
          beneficial interests in any other entities, nor is Tun Resources a
          party to any agreements of any nature to acquire any such shares or
          beneficial interests or to acquire or lease any other business
          operations;

     (m)  Tun Resources will have good and marketable title to the Assets, free
          and clear of all material liens, mortgages, charges, costs, expenses,
          liabilities and encumbrances of every nature and kind whatsoever; and

     (n)  there are no suits or proceedings at law or equity before or by any
          federal, provincial, municipal or other governmental department,
          commission, board, bureau, agency or instrumentality, which could
          adversely affect the business of Tun Resources or the purchase and
          sale herein contemplated.

3.4  The Vendor acknowledges and agrees that the Purchaser has entered into this
     Agreement relying on the warranties and representations and other terms and
     conditions hereof.

4.   REPRESENTATIONS AND WARRANTIES OF THE PURCHASER

4.1  The Purchaser represents and warrants to the Vendor (the Vendor relying on
     such representations and warranties in entering into this Agreement) that
     as of the date hereof:

     (a)  the Purchaser is a corporation duly incorporated under the laws of the
          State of Colorado, is validly existing and in good standing with
          respect to the filing of annual returns, and has the authority and
          capacity to enter into this Agreement and to carry out the
          transactions contemplated hereby;

<PAGE>

     (b)  all information with respect to the business activities of the
          Purchaser publicly disclosed by the Purchaser is true and correct;

     (c)  all necessary corporate actions have been or will be taken prior to
          Closing to authorize the Purchaser to enter into and perform this
          Agreement and this Agreement constitutes a legal, valid and binding
          obligation of the Purchaser enforceable against the Purchaser in
          accordance with its terms;

     (d)  the entering into of this Agreement and the transactions contemplated
          hereby will not result in the violation or breach of any of the terms
          and provisions of any indenture, lease or agreement, written or oral,
          to which the Purchaser is a party or by which the Purchaser is bound
          or affected;

     (e)  the entering into of this Agreement by the Purchaser and the
          completion by the Purchaser of the purchase of the Tun Resources
          Shares or the exercise of the Option pursuant hereto will not result
          in the violation of any law of the State of Colorado or the laws of
          the United States of America applicable therein;

     (f)  the Purchaser has not made any arrangements, commitments or
          undertakings for the payment of any finder's fees, commissions or
          brokerage fees in respect of the transactions contemplated by this
          Agreement for which the Vendor will have any liability;

     (g)  the entering into of this Agreement and the transactions contemplated
          hereby will not result in the violation of any of the terms and
          provisions of the constating documents or bylaws of the Purchaser or
          the Purchaser's Listing Agreement with the NASD's OTCBB or the Form
          211s filed by its market makers with the NASD; and

     (h)  The Purchaser is not in default of any requirements of the Securities
          Exchange Act of 1934 or the Securities Act of 1933 and the rules and
          regulations thereunder or of the rules and policies of the NASD as
          applied to the OTCBB system of electronic trading.

4.3  The Purchaser acknowledges and agrees that the Vendor has entered into this
     Agreement relying on the warranties and representations and other terms and
     conditions hereof.

5.   COVENANTS OF THE VENDORS

5.1  The Vendors covenant and agree that they will:

     (a)  cause to be taken all reasonably necessary steps, actions and
          corporate proceedings on the part of Tun Resources (including the
          approval of this Agreement by the directors of Tun Resources) to
          enable it to vest a good and marketable title to the Tun Resources
          Shares in the Purchaser, free and clear of all liens, mortgages,
          encumbrances, equities or claims of every nature and kind whatsoever;

<PAGE>

     (b)  if necessary, forthwith after the execution of this Agreement, obtain
          all necessary consents that may be required pursuant to the Assets in
          respect of the acquisition by the Purchaser of the Tun Resources
          Shares and make Mr. Tun Aye Sai the Chairman of the Joint Ventures (if
          he is not already);

     (c)  forthwith after the Closing of the transactions contemplated in this
          Agreement, confirm the appointment of Mr. Tun Aye Sai to the Board of
          Directors of Tun Resources; and

     (d)  take all reasonably necessary steps and perform all reasonable acts
          necessary to register the transfer of Tun Resources Shares to the
          Purchaser as these transfers occur.

6.   SURVIVAL OF REPRESENTATIONS, WARRANTIES AND COVENANTS

6.1  All representations, warranties, covenants and agreements made by the
     Vendor in this Agreement or pursuant hereto shall, unless otherwise
     expressly stated, survive the Closing and the payment of the Purchase
     Price.

6.2  All representations, warranties, covenants and agreements made by the
     Purchaser in this Agreement or pursuant hereto shall, unless otherwise
     expressly stated, survive the Closing, execution of further conveyances,
     the payment of the Purchase Price and any investigation at any time made by
     or on behalf of the Vendor.

7.   INDEMNITY

7.1  The Vendor and the Purchaser (the "Indemnifying Party") hereby agree to
     indemnify each the other (the "Indemnified Party") for, and to hold the
     Indemnified Party harmless against any and all costs, expenses (including
     legal fees on a solicitor and his own client basis), damages, liabilities
     and losses suffered or incurred by the Indemnified Party in connection with
     its reliance upon any of the representations, warranties or covenants of
     the Indemnifying Party set forth herein or contained in any document or
     certificate delivered by the Indemnifying Party pursuant hereto, in the
     event that any of such representations or warranties should prove to be
     inaccurate or untrue, or in the event that any of such covenants should be
     breached by the Indemnifying Party.

8.   CONDITIONS PRECEDENT TO PURCHASER'S OBLIGATIONS

8.1  Notwithstanding anything herein contained, the obligation of The Purchaser
     to complete the purchase of the Tun Resources Shares hereunder is subject
     to the following conditions:

     (a)  the representations and warranties of the Vendors contained in this
          Agreement shall be true as of Closing;

     (b)  all of the covenants, agreements and deliveries of the Vendors to be
          performed on or before the Closing pursuant to the terms of this
          Agreement shall have been duly performed;

<PAGE>

     (c)  prior to the Closing, Tun Resources shall not have experienced any
          event or condition or taken any action of any character or have become
          aware of any action of any character that would adversely affect the
          Assets, or financial condition of Tun Resources so as to materially
          reduce the value of the Assets to the Purchaser;

     (d)  The Purchaser and its counsel in their sole discretion are satisfied
          that at the Closing:

          (i)  The Purchaser will acquire good and valid title to the Tun
               Resources Shares free and clear of liens, charges and
               encumbrances (subject to section 2.4); and

          (ii) this transaction will not be subject to being set aside under any
               applicable insolvency, bankruptcy, or similar legislation;

     (e)  the transactions contemplated by this Agreement shall have been duly
          approved by the boards of directors of Tun Resources, the Purchaser,
          and by the CDNX and the BCSC, if necessary; and

     (f)  no federal, provincial, regional or municipal government or any agency
          thereof shall have enacted any statute, regulation or bylaws or
          announced any policy that will materially and adversely affect the
          Assets or the right of Tun Resources to the full enjoyment of the
          Assets.

8.2  The foregoing conditions are for the exclusive benefit of the Purchaser and
     such conditions may be waived in whole or in part by the Purchaser on or
     prior to the Closing by delivery to the Vendor of a written waiver to that
     effect, signed by the Purchaser.

9.   CONDITIONS PRECEDENT TO OBLIGATIONS OF THE VENDOR

9.1  Notwithstanding anything herein contained the obligation of the Vendor to
     complete the sale hereunder is subject to the following conditions:

     (a)  the representations and warranties of the Purchaser contained in this
          Agreement shall be true as of the Closing;

     (b)  The Purchaser shall have performed and complied with all covenants,
          agreements and conditions required by this Agreement to be performed
          or complied with by it at or prior to the Closing; and

     (c)  the transactions contemplated by this Agreement shall have been duly
          approved by the boards of directors of Tun Resources, the Purchaser,
          and by the CDNX and the BCSC, if necessary.

9.2  The foregoing conditions are for the exclusive benefit of the Vendor and
     any such condition may be waived in whole or in part by the Vendor at or
     prior to the time of Closing by delivering to the Purchaser a written
     waiver to that effect, signed by the Vendor.

<PAGE>

10.  VENDORS' DELIVERIES

10.1 At the Closing the Vendor shall deliver or cause to be delivered to the
     Purchaser or to the Purchaser's agent:

     (a)  a resolution of the board of directors of Tun Resources approving the
          transfer of 80% of the Tun Resources Shares to the Purchaser;

     (b)  subject to section 2.4, share certificates for 80% of Tun Resources
          Shares duly endorsed for transfer;

     (c)  the corporate records and seals of Tun Resources including, without
          limiting the generality of the foregoing, Tun Resources' constating
          documents and all minutes and resolutions of Tun Resources' directors
          and shareholders;

     (d)  resignations of the directors of Tun Resources as otherwise required
          herein and releases by all such directors and officers of Tun
          Resources of all claims they have against Tun Resources, conditional
          on the completion of the sale of the Tun Resources Shares pursuant
          hereto; and

     (e)  copies of all documents (including, without limitation, records,
          correspondence and contracts relating to the Joint Venture Agreements
          and the Joint Ventures) that have not been previously delivered before
          Closing and that the Purchaser in its reasonable opinion considers to
          be necessary or desirable for the conduct by the Purchaser of any
          activities related to the Assets.

11.  PURCHASER'S DELIVERIES

11.1 At the Closing, The Purchaser shall deliver or cause to be delivered share
     certificate(s) for the Purchaser Shares registered in the names of the
     Vendor.

12.  LOSS OR DAMAGE TO THE ASSETS PRIOR TO CLOSING

12.1 Until Closing, the Vendor shall cause Tun Resources to, and Tun Resources
     shall continue to, satisfy and comply with its obligations under the Joint
     Venture Agreements and the Joint Ventures and shall not make or initiate
     any actions that could result in the default in or breach of any term,
     condition, provision or obligation to be performed under the Joint Venture
     Agreements or the Joint Ventures which would impair or result in the loss
     of Tun Resources' interest in the Assets or adversely affect the business
     of Tun Resources or the purchase and sale herein contemplated.

13.  NOTICES

13.1 Any notice or other writing required or permitted to be given hereunder
     shall be deemed to be sufficiently given if personally delivered, if mailed
     postage prepaid in any post office in Canada, or if given by telegram,
     telecopier, or facsimile, addressed to the addresses given for the parties
     to this Agreement.

<PAGE>

13.2 Any such notice given as aforesaid shall be deemed to have been given to
     the parties hereto when delivered, if personally delivered, on the third
     business day following the date of mailing, if mailed, and on the same day
     as the telegraphing, telecopying, or facsimile transmission thereof, if
     telegraphed, telecopied, or transmitted by facsimile, PROVIDED HOWEVER,
     that during the period of any postal interruption in Canada any notice
     given hereunder by mail shall be deemed to have been given only as of the
     date of actual delivery of the same.

13.3 Any party may, from time to time by notice in writing given as aforesaid,
     change its address for the purposes of this section by giving notice of
     this change to the other parties.

14.  GENERAL PROVISIONS

14.1 Time shall be of the essence of this Agreement.

14.2 This Agreement contains the whole agreement between the Vendor and the
     Purchaser in respect of the purchase and sale of the Tun Resources Shares
     contemplated hereby and there are no warranties, representations, terms,
     conditions or collateral agreements, express, implied or statutory, other
     than expressly set forth in this Agreement.

14.3 This Agreement shall enure to the benefit of and be binding upon the
     parties hereto and, as applicable, their heirs, administrators, successors
     and assigns, and any reference herein to the Vendor or the Purchaser shall
     include, as applicable, their successors and assigns.

14.4 The parties hereto shall execute such further and other documents and do
     such further and other things as may be necessary to carry out and give
     effect to the intent of this Agreement.

14.5 This Agreement shall in all respects be governed by and be construed in
     accordance with the laws of the Province of British Columbia and the
     parties hereto agree to attorn to the courts thereof.

14.6 If any one or more of the provisions contained in this Agreement should be
     invalid, illegal or unenforceable in any respect in any jurisdiction, the
     validity, legality and enforceability of such provision or provisions shall
     not in any way be affected or impaired thereby in any other jurisdiction
     and the validity, legality and enforceability of the remaining provisions
     contained herein shall not in any way be affected or impaired thereby,
     unless in either case as a result of such determination this Agreement
     would fail of its essential purpose.

14.10 Unless otherwise indicated, all dollar amounts referred to in this
     Agreement are in Canadian dollars.

14.12 All costs and expenses (including, without limitation, the fees and
     disbursements of legal counsel and any investment advisors) incurred in
     connection with this Agreement and the transactions contemplated hereby
     shall be paid by the party incurring such expenses unless otherwise agreed
     to between the parties.

<PAGE>

14.13 This Agreement may be executed in one or more counterparts and by
     facsimile, each of which counterparts so executed shall constitute an
     original and all of which together shall constitute one and the same
     agreement.

14.14 The parties hereto acknowledge that Maitland & Company represents the
     Vendor and has provided no legal advice with respect to this agreement to
     any other party. The parties hereby acknowledge that they have been advised
     to seek independent legal advice with respect to this agreement and the
     Purchaser hereby agrees to hold harmless and indemnify Maitland & Company
     with respect to any claims brought by other parties regarding legal advice
     with respect to this agreement.

14.15 The parties undersigned have read, acknowledged, understood and accepted
     or, in the case of Tun Resources, consented to, the terms of the offer
     above.

IN WITNESS WHEREOF this Agreement has been executed by the parties hereto as of
the day and year first above written.

GOLDEN THUNDER RESOURCES LTD.

Signature on File
----------------------------------
Authorized Signatory

VEGA-ATLANTIC CORPORATION

Signature on File
---------------------------------
Authorized Signatory

The terms of the above offer are hereby acknowledged and consented to:

TUN RESOURCES INC.

Signature on File
-------------------------------
Authorized Signatory

<PAGE>

Schedule "A"

INTEREST IN JOINT VENTURE COMPANIES

1.   Yunnan Yuntong Exploration Co. Ltd. - Tun Resources Inc. holds a 60%
     interest

2.   Yunnan Lutong Geology Exploration Co. Ltd. - Tun Resources Inc. holds a 70%
     interest

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