EXHIBIT 4.13

              Option Agreement amended as of July 8, 2005, between

       Bulakashu Mining Company Ltd., Marasa Gold Corp., 0724000 BC Ltd.,
             Baradero Resources Limited and Magellan Gold (BVI) Inc.



<PAGE>


                                OPTION AGREEMENT


THIS AGREEMENT is made as of the 8th day of July, 2005

BETWEEN:


                  BULAKASHU  MINING  COMPANY  LTD,  a Kyrgyz  limited  liability
                  company with an address of 37, Baitik Baatyr St.,  Oktyabrskiy
                  district, Bishkek, 720005, Kyrgyz Republic

                  (hereinafter called "BMC")

                  OF THE FIRST PART

A N D:

                  MARSA GOLD CORP., a Kyrgyz limited  liability  company with an
                  address of Kyrgyz Republic, Bishkek, microregion 11, 6-46

                  (hereinafter called "Marsa")

                  OF THE SECOND PART

A N D:

                  CENTRASIA  MINING CORP.  (FORMERLY  "MAGELLAN GOLD CORP."),  a
                  British Columbia  corporation with an address of 300 - 1055 W.
                  Hastings St., Vancouver, BC V6E 2E9, Canada

                  (hereinafter called "Centrasia")

                  OF THE THIRD PART


                  BARADERO  RESOURCES LTD., a British Columbia  corporation with
                  an address of 1305 - 1090 West Georgia St., Vancouver,  BC V6E
                  3V7, Canada

                  (hereinafter called "Baradero")

                  OF THE FOURTH PART

A N D:

                  MAGELLAN GOLD (BVI) INC., a British Virgin Islands corporation
                  with  an  address  of  c/o  HWR  Services  Limited,  Craigmuir
                  Chambers,  P.O.  Box 71, Road Town,  Tortola,  British  Virgin
                  Islands

                  (hereinafter called "Magellan Gold BVI")

                  OF THE FIFTH PART


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                                      -2-




RECITALS:

A.       Marsa, Aitas Mining Company ("Aitas",  a Kazakhstan  corporation),  BMC
         and  Centrasia  are all of the  parties  to a  Letter  Agreement  dated
         September  24,  2004  (the  "Original  Agreement")  pursuant  to  which
         Centrasia  was  granted  an option by Marsa and Aitas to acquire a 100%
         interest  in BMC  from  each  of  Marsa  and  Aitas,  each  as to a 50%
         interest.

B.       Marsa,  Aitas,  BMC  and  Centrasia  are all of the  parties  to a Loan
         Agreement dated September 24, 2004 (the "Loan  Agreement")  pursuant to
         which  Centrasia  advanced  US$110,000  (the  "Loan")  to BMC  which is
         further  evidenced  by a demand  promissory  note  (the  "Note")  dated
         September 24, 2004 in the original amount of US$110,000, made by BMC in
         favour of Centrasia.

C.       Aitas and Marsa guaranteed  repayment of the Note pursuant to a written
         Guarantee  (the  "Original  Guarantee")  dated  September  24, 2004 and
         secured  their  respective  obligations  under the  Original  Guarantee
         pursuant to Pledge  Agreements  (the "Aitas  Pledge" and the  "Original
         Pledge",  respectively)  dated  September  24, 2004,  pursuant to which
         Aitas and Marsa pledged to Centrasia all of their respective  interests
         in BMC.

D.       Pursuant  to  an  Amending   Agreement  dated  January  18,  2005,  the
         respective parties  acknowledged that Aitas had recently withdrawn from
         its membership interest in BMC and consequently Aitas was released from
         its obligations under the Original Agreement,  the Loan Agreement,  the
         Original  Guarantee and the Aitas Pledge. Any reference to the Original
         Agreement  or  the  Loan  Agreement  hereunder  is a  reference  to the
         Original  Agreement  or the  Loan  Agreement  as  amended  by the  said
         Amending Agreement.

E.       Pursuant to a letter  agreement dated March 17, 2005 between  Baradero,
         Centrasia and the  shareholders  of Centrasia (the "Pubco  Agreement"),
         the shareholders of Centrasia agreed to exchange all of their shares of
         Centrasia for shares of Baradero,  which is a publicly  trading company
         whose shares trade on the TSX Venture Exchange in Canada (ticker "BRH")
         and on the Over The Counter  Bulletin Board market in the United States
         (ticker "BRHAF").

F.       In anticipation of closing of the Pubco Agreement,  Baradero has caused
         two  companies  to be  incorporated  in  the  British  Virgin  Islands,
         Magellan  Holdings (BVI) Corp.  ("Magellan  Holdings  BVI",  which is a
         direct  wholly owned  subsidiary  of Baradero)  and Magellan  Gold BVI,
         which is a direct wholly owned subsidiary of Magellan Holdings BVI.

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                                      -3-


G.       It is anticipated that on closing of the  transactions  contemplated by
         the Pubco Agreement, Baradero will change its name to "Centrasia Mining
         Corp." and Centrasia will change its name as a consequence.

H.       It is in order to  replace  the  Original  Guarantee  and the  Original
         Pledge with a new  guarantee and a new pledge  agreement.


I.       The Pubco  Agreement  requires  that certain  amendments be made to the
         Original  Agreement,  and the parties hereto have agreed to replace the
         Original Agreement with this Agreement as hereinafter provided.



NOW THEREFORE,  for and in consideration of the premises, and for other good and
valuable   consideration   the  receipt  and  sufficiency  of  which  is  hereby
acknowledged, the parties hereto do hereby agree as follows:

1.       The  Recitals  set forth above are  acknowledged  by all of the parties
         hereto to be true and correct and are incorporated  into this Agreement
         by this reference.

2.       (A)  Marsa  hereby  agrees  to  execute  a new  guarantee  (the  "Marsa
         Guarantee")  to replace  the  Original  Guarantee,  which will  provide
         security  for the  repayment  of the Loan and all  present  and  future
         indebtedness of BMC to Centrasia, including under this Agreement.

         (B) Marsa hereby agrees to execute a new pledge  agreement  (the "Marsa
         Pledge") to replace the Original  Pledge,  which will provide  security
         for the  repayment of the Loan and all present and future  indebtedness
         of BMC to Centrasia, including under this Agreement.

3.       On the dates set forth in Section 11 below and subject to the terms and
         conditions of this Agreement,  Marsa will cause the Charter of BMC (the
         "BMC  Charter")  to be  amended to provide  that  Centrasia  shall have
         acquired a  participating  interest  in BMC free and clear from any and
         all liens, charges or encumbrances  whatsoever (hereinafter referred to
         as a "Participating Interest").

4.       Marsa   acknowledges   that  immediately   after  the  closing  of  the
         transactions  contemplated by the Pubco  Agreement,  all of Centrasia's
         right,  title and interest in this Agreement,  the Loan Agreement,  the
         Marsa Guarantee and the Marsa Pledge shall be assigned to Magellan Gold
         BVI and Marsa hereby  consents to such assignment and agrees to execute
         all  collateral  agreements and documents as may be necessary to effect
         such assignment.  Upon such assignment,  Magellan Gold BVI shall assume
         all of the rights, privileges, obligations and liabilities of Centrasia
         under this Agreement,  the Loan Agreement,  the Marsa Guarantee and the
         Marsa Pledge.

5.       In addition to the  Intercompany  Loans to be made by  Centrasia to BMC
         (as defined in section 10), Centrasia must make share and cash payments
         to Marsa to maintain its interest under this Agreement.  Subject to the
         closing of the transactions  contemplated by the Pubco Agreement and in
         consideration  for the transfer to its subsidiary  Magellan Gold BVI at


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                                      -4-


         such  closing of  Centrasia's  interest  in this  Agreement,  the share
         payments  shall consist of 1,025,000  shares in the capital of Baradero
         (the "Purchase Shares"),  to be issued to Marsa on the dates and in the
         amounts  shown  below  unless,  at least 10 days before each such date,
         Marsa delivers a written direction to Baradero  instructing Baradero to
         issue the  Purchase  Shares to a nominee,  in which event the  Purchase
         Shares will be issued to the named nominee.

         The Purchase Shares will be issued as follows:

         -----------------------------------------------------------------------
         Date                                             No. of Purchase Shares
         -----------------------------------------------------------------------

         On the date of closing of the Pubco Agreement            200,000 Shares
         January 2, 2006                                          200,000 Shares
         January 2, 2007                                          250,000 Shares
         January 2, 2008                                          375,000 Shares
                                                                ---------
         Total:                                                 1,025,000 Shares
                                                                =========
         -----------------------------------------------------------------------

         The cash payments  shall be the  aggregate  sum of  US$120,000  paid as
         follows:

         -----------------------------------------------------------------------
         Date                                                     US$ to be Paid
         -----------------------------------------------------------------------

         January 2, 2005(which Marsa hereby acknowledges has been paid)  $40,000

         On or before the earlier of  (i) five days after                $40,000
         the date of closing of the Pubco Agreement; or
         (ii) September 1, 2005, and subject to the
         amendment of the BMC Charter as provided in
         section 13

         On or before January 2, 2006                                    $40,000
                                                                         -------
         Total:                                                         $120,000
                                                                         =======
         -----------------------------------------------------------------------

6.       (A) The  Purchase  Shares  will be subject to a four month hold  period
         from the date they are issued in each case from any sale in  applicable
         jurisdictions  in Canada  or  through  the TSX  Venture  Exchange  (the
         "Exchange"),  and  certain  of the  Purchase  Shares  may be subject to
         escrowing in accordance with the rules of the Exchange.


<PAGE>
                                      -5-


         (B) The Purchase Shares have not been and will not be registered in the
         United  States  SECURITIES  ACT OF 1933 (the "1933 Act"),  or under any
         state  securities or "blue sky" laws of any state of the United States,
         and,  unless so  registered,  may not be  offered or sold in the United
         States or to U.S.  Persons  (as such term is  defined in  Regulation  S
         under the SECURITIES  ACT OF 1933, as amended,  of the United States of
         America)  except pursuant to an exemption from, or in a transaction not
         subject to, the registration requirements of the 1933 Act. As such, the
         Purchase  Shares  will be  subject to a one year hold  period  from and
         after  the date they are  issued  in each case from sale in the  United
         States.

         (C) Marsa will provide and execute all  representations  and collateral
         agreements as are necessary to ensure that the issuance of the Purchase
         Shares  complies with the  requirements  of all  applicable  securities
         legislation and the rules of the Exchange.

7.       Baradero will issue the Purchase Shares from treasury as fully-paid and
         non-assessable shares in the capital of Baradero, free and clear of all
         liens,  charges and  encumbrances  except as expressly  provided for in
         Section 6 above.

8.       (1)      BMC holds Exploration Licence No. AP-48 (the "Licence") issued
                  on March 28, 2005 by the State  Agency for Geology and Mineral
                  Resources  under the  Government  of the Kyrgyz  Republic (the
                  "Geology Agency").  The Licence is an exploration licence that
                  permits  BMC to explore  for gold in the area  described  in a
                  Licence  Agreement  dated March 28,  2005  between BMC and the
                  Geology Agency (which area is  hereinafter  referred to as the
                  "Bulakashu Property"). For the purposes of this Agreement, the
                  "Closing Date" shall be deemed to refer to the date upon which
                  Centrasia  has succeeded to a 100%  Participating  Interest in
                  BMC pursuant to  sub-section  11(d),  and an "Interim  Closing
                  Date"  refers  to a date  when a loan  made  by  Centrasia  is
                  converted   into  a   Participating   Interest   pursuant   to
                  sub-sections  11(a) to (c).  From the date  hereof  until  the
                  Closing Date (the "Pre-Closing Period"), BMC will:

                  (a)      not  sell or  dispose  of the  Licence  or any of its
                           other   assets    (collectively,    hereinafter   the
                           "Assets");

                  (b)      preserve, protect and maintain the Assets;

                  (c)      carry  on  its   business  as  a  natural   resources
                           exploration and development  company (the "Business")
                           in the ordinary course  consistent with past practice
                           and  in   compliance   with  all   applicable   laws,
                           regulations    and   rules   of   all    governmental
                           authorities;

                  (d)      not suffer or permit any  encumbrance to attach to or
                           affect any of the Assets;

                  (e)      not enter into any transaction  which could cause any
                           representation  or warranty of BMC or Marsa contained
                           herein  to  be  incorrect  on  the  Closing  Date  or
                           constitute  a breach of any  covenant or agreement of
                           BMC or Marsa contained herein;

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                                      -6-




                  (f)      give to Centrasia, Baradero and Magellan Gold BVI and
                           their  respective  counsel,   accountants  and  other
                           representatives,  full access, during normal business
                           hours  throughout the Pre-Closing  Period,  to all of
                           BMC's books and records  relating to its Business and
                           the  Assets,   and  promptly  furnish  to  Centrasia,
                           Baradero or Magellan  Gold BVI during that period all
                           such information as may request by any such party;

                  (g)      on or  before  each  Interim  Closing  Date  and  the
                           Closing Date, obtain any and all required consents of
                           any third parties in respect of each  conversion of a
                           loan made by Centrasia into a Participating  Interest
                           referenced in sub-sections 11(a) through (d); and

                  (h)      take or  cause  to be  taken  all  corporate  action,
                           including  obtaining  BMC  participant   approval  if
                           necessary,  to  validly  and  effectively  ratify the
                           execution   and  delivery  of  this   Agreement   and
                           authorize    the   closing   of   the    transactions
                           contemplated hereby;


         (2)      Marsa as the sole participant of BMC will not make any changes
                  in the  Business or Assets of BMC as permitted by Article 12.1
                  of the BMC  Charter  without  the  prior  written  consent  of
                  Centrasia and Baradero.

9.       (1)      BMC and Marsa each  acknowledge  that the Loan and all present
                  and future  indebtedness of BMC to Centrasia,  including under
                  this  Agreement,  shall be secured by the Marsa  Guarantee and
                  the Marsa  Pledge,  which shall be continuing  obligations  of
                  Marsa until the Closing Date.

         (2)      BMC and  Marsa  also  hereby  acknowledge  that the  Agreement
                  between  BMC and Marsa on joint  activity  for the  purpose of
                  carrying  of the  exploration  works  dated  July 25,  2004 is
                  hereby terminated.

10.      Subject to the terms and conditions of this  Agreement,  Centrasia will
         commit to fund BMC's exploration program on the Bulakashu Property,  by
         way  of  intercompany  loans  including  the  Loan  (collectively,  the
         "Intercompany  Loans") to be advanced  pursuant to mutually agreed upon
         budgets from time to time,  in the following  total amounts  during the
         following periods:

            Calendar Year 2005:     Cdn$200,000(deemed to be equal to US$160,000
                                    (at Cdn$1 = US$0.80),the "2005  Calendar
                                     Year Loan")

            Calendar Year 2006:     US$690,000 (the "2006 Calendar Year Loan")
            Calendar Year 2007:     US$650,000 (the "2007 Calendar Year Loan")
            Calendar Year 2008:     US$750,000 (the "2008 Calendar Year Loan")

         At such time as BMC has defined on the Bulakashu  Property an indicated
         reserve (as defined by JORC or CIM reserve  standards) of not less than
         300,000 ounces of gold, Centrasia will initiate a pre-feasibility study
         as a possible pre-cursor to production.  If Marsa desires to initiate a
         pre-feasibility  study of the  Bulakashu  Property  it may do so at any
         time, at its sole cost and expense.


<PAGE>
                                      -7-



11. The Intercompany Loans shall be converted to Participating  Interests in the
following amounts at the following dates:

         (a)      At the end of  calendar  year  2005,  the  Loan  and the  2005
                  Calendar  Year  Loan  shall be  converted  to a  Participating
                  Interest equal to 10.5% of the total Participating Interest in
                  BMC on December 31, 2005 and Marsa shall cause the BMC Charter
                  to be amended accordingly.

         (b)      At the end of calendar year 2006,  the 2006 Calendar Year Loan
                  shall be converted to a Participating Interest equal to 27% of
                  the total Participating  Interest in BMC on December 31, 2006,
                  increasing Centrasia's Participating Interest in BMC to 37.5%,
                  and  Marsa   shall   cause  the  BMC  Charter  to  be  amended
                  accordingly.

         (c)      At the end of calendar year 2007,  the 2007 Calendar Year Loan
                  shall be converted to a Participating Interest equal to 30% of
                  the total Participating  Interest in BMC on December 31, 2007,
                  increasing Centrasia's Participating Interest in BMC to 67.5%,
                  and  Marsa   shall   cause  the  BMC  Charter  to  be  amended
                  accordingly.

         (d)      At the end of calendar year 2008,  the 2008 Calendar Year Loan
                  shall be converted to a Participating  Interest equal to 32.5%
                  of the total  Participating  Interest in BMC on  December  31,
                  2008, increasing Centrasia's  Participating Interest in BMC to
                  100%,  and Marsa  shall  cause the BMC  Charter  to be amended
                  accordingly and shall cease to be a participant in BMC.

         The Intercompany Loans shall be converted to Participating Interests by
         means of execution of  agreements  between Marsa Gold and Centrasia and
         taking other necessary actions in accordance with applicable law.



12.      If, during any of calendar years 2005,  2006,  2007 or 2008,  Centrasia
         fails to fund the respective  Intercompany Loan for that year, or issue
         the Purchase  Shares as and when required  pursuant to Section 5 above,
         or commits any other  material  breach of this  Agreement,  Marsa' sole
         remedy shall be the right to "put" back to  Centrasia  all or a portion
         of the  Purchase  Shares that Marsa has  received up to the date of the
         put (the total number of such Purchase  Shares  received being referred
         to as the "Total  Purchase  Shares" and the number of  Purchase  Shares
         actually put to  Centrasia  being  referred to as the "Put  Shares") in
         exchange for a pro-rata  portion of the  Participating  Interests  that
         Centrasia has then received  equal to the product of (X) divided by (Y)
         multiplied by 100 and expressed as a percentage,  where (X) is equal to
         the  number of Put  Shares  and (Y) is equal to the number of the Total
         Purchase Shares. In such event, (i) the then outstanding balance of the
         current  Intercompany  Loan  shall be  forgiven,  (ii)  Marsa  shall be
         entitled to keep  whatever  amounts  Centrasia has already then paid to
         them on account of the cash portion of the purchase price and (iii) the
         parties  shall  thereafter  be  released  from any  further  obligation
         hereunder.


<PAGE>
                                      -8-


13.      The parties  agree to use their best efforts to prepare an amendment to
         the BMC Charter to include provisions regarding Board of Directors. The
         Board of Directors shall consist of three members, two of whom shall be
         Centrasia  nominees and the third shall be a nominee of Marsa.  The BMC
         Board  shall  be  responsible   for  designing  and   implementing   an
         exploration  program  pursuant  to  the  budget  approved  by  BMC  and
         Centrasia  during each  calendar  year as required by Section 10 above.
         Once the  amendment  has been  approved by all  parties,  Marsa and BMC
         agree to take all  necessary  steps to bring the  amendment  to the BMC
         Charter into effect at the earliest  possible date, and in any event on
         or before September 1, 2005.


14.      Marsa and BMC do hereby jointly and severally  represent and warrant to
         Centrasia,  Baradero  and  Magellan  Gold  BVI,  with the  intent  that
         Centrasia,   Baradero  and  Magellan   Gold  BVI  shall  rely  on  such
         representations  and  warranties in entering into this Agreement and in
         closing the transactions contemplated hereby, that:

         (a)      Marsa and BMC are each corporations duly incorporated, validly
                  existing  and in good  standing  under the laws of the  Kyrgyz
                  Republic,  and Marsa has the  power  and  capacity  to own and
                  dispose of the Participating Interests presently held by it;

         (b)      BMC has the  power  and  corporate  capacity  to  carry on its
                  Business;

         (c)      the Assets are all of the assets  necessary  or  desirable  to
                  carry on its Business;

         (d)      Marsa  is the  sole  participant  of BMC and  owns  all of the
                  right,  title and interest in and to the entire  Participating
                  Interest  in BMC,  and no person has any right to acquire  any
                  Participating Interest in BMC from Marsa or otherwise;

         (e)      no person has any right to acquire any Participating  Interest
                  of BMC from BMC, whether by exercise of options, conversion of
                  convertible securities or otherwise;

         (f)      BMC owns all of the right,  title and  interest in and to each
                  of the Assets, free and clear of all liens, charges,  pledges,
                  security interests and encumbrances whatsoever;

         (g)      on  each  Interim  Closing  Date  and  on  the  Closing  Date,
                  Centrasia  will  receive all right,  title and interest in the
                  Participating  Interests  to which it is entitled on each such
                  respective  date,  free and clear of all  liens,  charges  and
                  encumbrances;

         (h)      all   of   the   licences,   permits,   approvals,   consents,
                  certificates,   registrations   and   authorizations   as  are
                  necessary or  desirable in the ordinary  course of the conduct
                  of its  Business or  otherwise  for the use of the Assets have
                  been obtained,  are in good standing and are not terminable on
                  the  basis  of the  creation  of  Participating  Interests  in
                  Centrasia;


<PAGE>
                                      -9-



         (i)      all  registrations or filings with any  governmental  offices,
                  domestic  and  foreign,  as  are  necessary  or  advisable  to
                  evidence  or protect or preserve  any of the Assets  which are
                  necessary to or used in its Business (the  "Rights") have been
                  made and the Rights are valid and enforceable;

         (j)      there is no legal action  pending or  threatened by any person
                  or entity relating to the Participating  Interests, the Assets
                  or the  Business  and Marsa is not aware of any adverse  claim
                  which has ever been, or is currently being, threatened against
                  the Participating Interests, the Assets or the Business or any
                  of them,  nor is it aware of any claim by any person or entity
                  that any of the Rights is or may be invalid or unenforceable;

         (k)      BMC has not, in any manner whatsoever,  granted,  transferred,
                  licensed or assigned or permitted to be granted,  transferred,
                  licensed  or  assigned  any  right  or  interest  of any  kind
                  whatsoever  in the  Assets to any person or entity and BMC has
                  not otherwise encumbered the Assets;

         (l)      no  authorization,  approval or other action by, and no notice
                  to or filing with,  any  governmental  authority or regulatory
                  body is required or desirable in connection  with the issuance
                  of creation of Participating  Interests in Centrasia  pursuant
                  to this Agreement, save and except for the necessary amendment
                  to the BMC Charter;

         (m)      no  representation  or  warranty  of  BMC  or  Marsa  in  this
                  Agreement contains any untrue statement of a material fact;

         (n)      the  representations and warranties of BMC and Marsa contained
                  in this  Agreement  do not omit to  state  any  material  fact
                  necessary to make any of them not  misleading to a prospective
                  purchaser of BMC seeking full, true and plain disclosure as to
                  BMC;

         (o)      the  execution   and  delivery  of  this   Agreement  and  the
                  completion of the transactions  contemplated by this Agreement
                  have  been  duly  and  validly  authorized  by  all  necessary
                  corporate  action  on the part of each of BMC and  Marsa,  and
                  this  Agreement   constitutes  a  legal,   valid  and  binding
                  obligation of each of BMC and Marsa  enforceable  against each
                  such party in accordance with its terms;

         (p)      there will be no change  made to the  General  Director of BMC
                  until such time as the BMC Charter is amended to provide for a
                  Board of Directors as set out in section 13;

         (q)      the BMC Charter complies with all applicable Kyrgyz laws; and

         (r)      neither the execution and delivery of this Agreement,  nor the
                  completion  of the  purchase  and  sale  contemplated  by this
                  Agreement will:

<PAGE>
                                      -10-



                  (i)      violate  any  of  the  terms  and  provisions  of the
                           constating  documents  or bylaws or articles of Marsa
                           or  BMC,  or  any  order,  decree,  statute,  by-law,
                           regulation,  covenant or  restriction  applicable  to
                           Marsa, BMC or any of the Assets;

                  (ii)     give any person the right to  terminate,  suspend the
                           operation of, cancel or remove any of the Assets; or

                  (iii)    result in any fees,  duties,  taxes,  assessments  or
                           other amounts relating to the Participating Interests
                           or any of the Assets becoming due or payable.


15.      Each of BMC and  Marsa  will  indemnify  and  hold  each of  Centrasia,
         Baradero and Magellan Gold BVI harmless from and against:

         (a)      any and all liabilities, whether accrued, absolute, contingent
                  or  otherwise,  existing at the Closing  Date and each Interim
                  Closing Date in connection  with the respective  Participating
                  Interests to be acquired by Centrasia;

         (b)      any  and  all  damages  or  deficiencies  resulting  from  any
                  misrepresentation, breach of warranty or non-fulfilment of any
                  covenant on the part of Marsa or BMC under this  Agreement  or
                  from any misrepresentation in or omission from any certificate
                  or other instrument furnished or to be furnished to Centrasia,
                  Baradero or Magellan Gold BVI under this Agreement; and


         (c)      any and all actions, suits, proceedings, demands, assessments,
                  judgments,  costs and legal and other expenses incident to any
                  of the foregoing.

16.      Centrasia,  Baradero  and  Magellan  Gold  BVI  jointly  and  severally
         represent  and  warrant to Marsa and BMC,  with the intent that each of
         Marsa and BMC shall rely on these  representations  and  warranties  in
         entering  into  this  Agreement  and  in  concluding  the  transactions
         contemplated hereby, that:

         (a)      Each  of  Centrasia,  Baradero  and  Magellan  Gold  BVI  is a
                  corporation  duly  incorporated,  validly existing and in good
                  standing under the laws of its jurisdiction of  incorporation,
                  has the power and  capacity to enter into this  Agreement  and
                  carry out its terms;

         (b)      Centrasia is currently  authorized to issue 10,000,000  common
                  shares,  each with a par  value of  US$0.001,  and  10,000,000
                  preferred shares, each with a par value of US$0.001. As at the
                  date of this Agreement  Centrasia has issued and outstanding a
                  total of 3,700,100 common shares and no preferred shares,  all
                  of which are validly issued and  outstanding as fully paid and
                  non-assessable shares;

         (c)      the  execution   and  delivery  of  this   Agreement  and  the
                  completion of the transactions  contemplated by this Agreement
                  have  been  duly  and  validly  authorized  by  all  necessary
                  corporate  action on the part of each of  Centrasia,  Baradero
                  and Magellan Gold BVI and this Agreement  constitutes a legal,
                  valid and binding  obligation  of each such party  enforceable
                  against each such party in accordance with its terms; and


<PAGE>
                                      -11-


         (d)      the Purchase Shares, when issued, will be issued as fully paid
                  and  non-assessable  shares  free  and  clear  of  all  liens,
                  charges, claims or encumbrances,  except as expressly provided
                  for in Section 6 of this Agreement.

17.      All  representations,  warranties,  covenants and agreements  made by a
         party in this  Agreement  shall,  unless  otherwise  expressly  stated,
         survive the execution of this Agreement,  each Interim Closing Date and
         the Closing Date.

18.      The obligation of each of Centrasia,  Baradero and Magellan Gold BVI to
         close the  transactions  contemplated by this Agreement,  including the
         obligation to deliver the Purchase Shares, is subject to the fulfilment
         by Marsa and BMC to the satisfaction of each of Centrasia, Baradero and
         Magellan  Gold BVI on or  before  the  Closing  Date  and each  Interim
         Closing Date, of the following conditions:

         (a)      that the  representations  and  warranties  of  Marsa  and BMC
                  contained in this Agreement and in any certificate or document
                  delivered pursuant to this Agreement or in connection with the
                  transactions  contemplated  hereby  shall be true at and as of
                  the  Closing  Date and each  Interim  Closing  Date as if such
                  representations  and  warranties  were  made at and as of such
                  time;

         (b)      that BMC shall not then be in default of the terms of the Loan
                  Agreement;

         (c)      that  there  shall be no legal or  administrative  restriction
                  preventing  BMC from  amending the BMC Charter,  and BMC shall
                  have amended the BMC Charter to include provisions regarding a
                  Board of Directors, as provided in section 13 above;

         (d)      that Marsa and BMC shall have  performed and complied with all
                  of the agreements,  covenants and conditions  required by this
                  Agreement to be performed or complied  with by it on or before
                  the Closing Date and each Interim Closing Date;

         (e)      that between the date of this  Agreement  and the Closing Date
                  and  each  Interim   Closing  Date,  no  change,   event,   or
                  circumstance has occurred which materially  adversely  affects
                  the Assets;

         (f)      that between the date of this  Agreement  and the Closing Date
                  and  each  Interim  Closing  Date,  there  has  not  been  any
                  substantial  loss,  damage,  or  destruction,  whether  or not


<PAGE>
                                      -12-


                  covered by  insurance,  to any of the Assets;  and (g) that no
                  legal or regulatory  action or proceeding  shall be pending or
                  threatened  on the Closing Date and each Interim  Closing Date
                  by any person to enjoin, restrict or prohibit the purchase and
                  sale of the Participating Interests.

         The  foregoing  conditions  are for the  exclusive  benefit  of each of
         Centrasia, Baradero and Magellan Gold BVI and any such condition may be
         waived in whole or in part by each such party at or before the  Closing
         Date by  delivering  to Marsa and BMC a written  waiver to that  effect
         signed by the respective party.



19.      On the Closing Date and each Interim Closing Date,  Marsa shall deliver
         or cause to be delivered to Centrasia:


         (a)      such bills of sale, transfer documents,  assignments,  in form
                  and content  satisfactory to Centrasia,  as are appropriate to
                  effectively  vest good and marketable  title to the applicable
                  Participating Interest in Centrasia to the extent contemplated
                  by this Agreement;

         (b)      any consents or approvals required to be obtained by Marsa for
                  the purpose of validly  creating the applicable  Participating
                  Interests to Centrasia;

         (c)      a certificate of each of Marsa and BMC dated as of the Closing
                  Date and each Interim  Closing  Date,  acceptable  in form and
                  content  to   Centrasia,   Baradero  and  Magellan  Gold  BVI,
                  certifying that:

                  (i)      the  Directors of each of the  respective  party have
                           passed resolutions duly authorizing the execution and
                           delivery of this  Agreement and the completion of the
                           transactions contemplated hereby; and

                  (ii)     the respective party's representations and warranties
                           contained  in  this  Agreement  are  true  as of  the
                           Closing Date and each Interim Closing Date;

         (d)      the legal opinion of the solicitors for Marsa and BMC, in form
                  and content satisfactory to Centrasia,  to the effect that all
                  necessary steps and corporate  proceedings  have been taken by
                  Marsa and BMC to permit  the  registration  of the  applicable
                  Participating  Interests  as  contemplated  hereby,  that this
                  Agreement and all documents and instruments delivered pursuant
                  hereto have been duly and validly  authorized,  executed,  and
                  delivered  by Marsa  and BMC and  will  constitute  valid  and
                  legally binding obligations of Marsa and BMC, and

         (e)      all  such  other   documents  and  instruments  as  Centrasia,
                  Baradero or Magellan Gold BVI may reasonably require.


<PAGE>
                                      -13-


20.      Marsa and BMC agree that they will cooperate with  Centrasia,  Baradero
         and Magellan Gold BVI in preparing financial  statements of BMC for the
         most recent calendar years prior to the closing of the Pubco Agreement,
         prepared  and audited in  accordance  with  Canadian  GAAP and GAAS and
         otherwise  meeting  the  requirements  of  the  Exchange,  the  British
         Columbia  Securities  Commission,  and, to the extend  applicable,  the
         United  States  Securities  and  Exchange  Commission,   together  with
         unaudited  reviewed  financial  statements  prepared in accordance with
         Canadian GAAP for any interim periods  following the most recent fiscal
         year end.

21.      Any notice  required or permitted to be given under this Agreement will
         be in  writing  and  may  be  given  by  hand  delivering,  sending  by
         electronic   facsimile   transmission  or  other  means  of  electronic
         communication  capable  of  producing  a printed  copy,  or  sending by
         overnight courier, the notice to the address of the party set out above
         and in the case of:

                  (a) Centrasia, Baradero or Magellan Gold BVI, with a copy to:

                           Axium Law Group
                           P.O. Box 49222
                           1055 Dunsmuir St. #3350, Bentall 4
                           Vancouver, BC V7X 1L2 CANADA

                           Attention: Michael C Varabioff
                           Fax: 604- 692-4900

                           and to:

                           Thomas, Rondeau
                           PO Box 10037, Pacific Centre
                           Suite 1925, 700 West Georgia St.
                           Vancouver, BC  V7Y 1A1  CANADA

                           Attention: Mr. James L. Harris
                           Fax: 604-688-6995

                  (b) Marsa, with a copy to:

                           c/o Bulakashu Mining Company LTD

                           Kyrgyz Republic,
                           Bishkek, Baitik Baatyra 37

                           Facsimile No.:  (996) (312) 55-94-34

         (or to such other  address or number as any party may specify by notice
         in  writing  to  another  party).  Any  notice  delivered  or  sent  by
         electronic   facsimile   transmission  or  other  means  of  electronic
         communication  capable of  producing a printed  copy on a business  day
         will be deemed  conclusively to have been effectively  given on the day
         the notice was delivered,  or the transmission was sent successfully to
         the  number  set out  above,  as the case may be.  Any  notice  sent by
         overnight courier will be deemed  conclusively to have been effectively
         given on the next business day after depositing with the courier.


<PAGE>
                                      -14-



22.      If under this Agreement or any document delivered under this Agreement,
         either  of Marsa  or BMC  become  obligated  to pay any sum of money to
         Centrasia,  then such sum may at the election of Centrasia, and without
         limiting  or  waiving  any right or remedy  for  Centrasia  under  this
         Agreement,  be set-off  against  and shall apply to any sum of money or
         security  owed by  Centrasia to Marsa or BMC until such amount has been
         completely set-off. This covenant shall survive the Closing.

23.      This Agreement  constitutes  the entire  agreement  between the parties
         with respect to the subject matter herein and in particular  supersedes
         and replaces the Original Agreement.

24.      Delivery of an executed copy of this Agreement by electronic  facsimile
         transmission  or other  means of  electronic  communication  capable of
         producing a printed copy will be deemed to be execution and delivery of
         this Agreement as of the date set forth on page one of this Agreement.

25.      Unless  otherwise  provided,  all dollar  amounts  referred  to in this
         Agreement are in lawful money of the United States.  26. This Agreement
         will enure to the benefit of and be binding  upon the parties and their
         respective administrators, successors,
         and assigns.

27.      Wherever there is any conflict  between any provision of this Agreement
         and any  present  or future  statute,  law,  ordinance,  or  regulation
         against  which the parties have no legal right to contract,  the latter
         will prevail;  but in such event the provision of this  Agreement  thus
         affected will be curtailed and limited only to the extent  necessary to
         bring it within the  requirements  of the law. If any term,  provision,
         covenant,  or condition of this Agreement or the application thereof to
         any  person or  circumstance  will,  at any time or to any  extent,  be
         invalid,  illegal,  voidable,  or unenforceable,  then the remainder of
         this Agreement or the application  thereof to persons or  circumstances
         other than those as to whom it is held invalid,  illegal,  voidable, or
         unenforceable will not be affected thereby,  and each term,  provision,
         covenants, and condition of this Agreement will be and remain valid and
         enforceable to the fullest extent  permitted by law. If any tribunal or
         Court of competent  jurisdiction deems any provision hereof (other than
         for the payment of money) unreasonable, then the said tribunal or Court
         may declare a reasonable  modification  hereof, and this Agreement will
         be valid and  enforceable,  and the parties hereto will be bound by and
         perform the same, as so modified.

28.      When the context hereof makes it possible,  the word "person" appearing
         in this  Agreement  includes  in its  meaning  any  firm  and any  body
         corporate or politic.

29.      This Agreement will be governed by and construed in accordance with the
         law of British  Columbia.  All disputes arising out of or in connection
         with this  Agreement,  or in respect of any defined legal  relationship
         associated  therewith  or derived  therefrom,  shall be referred to and
         finally  resolved by arbitration  in the English  language using a sole
         arbitrator  under  the  rules  of the  British  Columbia  International
         Commercial  Arbitration  Centre.  The appointing  authority or tribunal
         shall be the  British  Columbia  International  Commercial  Arbitration
         Centre.  The  case  shall  be  administered  by  the  British  Columbia
         International  Commercial  Arbitration  Centre in  accordance  with its
         Rules. The place of arbitration  shall be Vancouver,  British Columbia,
         Canada.


<PAGE>
                                      -15-



30.      This Agreement may be executed in several  counterparts,  each of which
         will be  deemed  to be an  original  and  all of  which  will  together
         constitute one and the same instrument.

31.      Delivery of an executed copy of this Agreement by electronic  facsimile
         transmission  or other  means of  electronic  communication  capable of
         producing a printed copy will be deemed to be execution and delivery of
         this Agreement as of the date of this Agreement.

32.      There are no representations,  warranties,  collateral  agreements,  or
         conditions  between  the parties  hereto  except as  specified  in this
         Agreement,  the Loan  Agreement,  the  Marsa  Guarantee  and the  Marsa
         Pledge.

33.      The parties will execute and deliver all such further documents,  do or
         cause to be done all such  further  acts and things,  and give all such
         further  assurances  as may be  necessary  to give  full  effect to the
         provisions and intent of this Agreement.

34.      Time is of the essence of this Agreement.

35.      Notwithstanding any other provision herein, the obligations of Baradero
         and Magellan Gold BVI under this Agreement are subject to completion of
         the  transactions  contemplated  by the Pubco  Agreement (as amended or
         replaced from time to time). If these transactions are not completed on
         or before  September 30, 2005,  then this  Agreement  shall be null and
         void so far as Baradero and Magellan Gold BVI are concerned and neither
         of those parties  shall have any  obligations  hereunder.  This section
         does not relieve  Centrasia  from its  obligation  to pay  US$40,000 to
         Marsa no later than September 1, 2005 pursuant to section 5 above.

36.      This Agreement is subject to its acceptance for filing by the Exchange.

IN WITNESS WHEREOF,  the parties hereto have signed this Agreement as of the day
and year first above written.



BULAKASHU MINING COMPANY LTD


Per: /s/ Oleg Kim
     ----------------------------
     Authorized Signatory


MARSA GOLD CORP.


Per: /s/ Dmitriy Vedeshkin-Ryabov
     ----------------------------
         Authorized Signatory

<PAGE>
                                      -16-


CENTRASIA MINING CORP.


Per: /s/ Douglas Turnbull
     ----------------------------
         Authorized Signatory


BARADERO RESOURCES LTD


Per: /s/ Nick DeMare
     ----------------------------
         Authorized Signatory


MAGELLAN GOLD (BVI) INC.


Per: /s/ Nick DeMare
     ----------------------------
         Authorized Signatory


<PAGE>