STRICTLY PRIVATE AND
CONFIDENTIAL
  June 18,
2008
  To:
  Mexoro
Minerals Ltd.
 C.
General Retana #706
 Col. San
Felipe
 Chihuahua,
Mexico  CP 31203
 
  Attention : Mario Ayub,
Chief Executive Officer
  
 Dear Mr.
Ayub:
  Re:
              Amendment
      to Letter of Intent dated May 2, 2008 (the “Letter of Intent”) between
      Mexoro Minerals Ltd. (“Mexoro”) and Paramount Gold and Silver Corp.
      (“Paramount”) with respect to the Proposed Strategic Alliance (the
      “Proposed Transaction”) between Mexoro and
  Paramount
  This
amendment (the “Amendment”) to the Letter of
Intent is further to the discussions to date between Mexoro and
Paramount.  The provisions of this Amendment, together with the Letter
of Intent, will confirm the present interest of the parties with respect to the
Proposed Transaction.
  Capitalized
terms used but not defined herein shall have the meaning ascribed thereto in the
Letter of Intent.
  The
undersigned agree to amend the Letter of Intent as follows:
 
 1.           Extension
of Term. The parties agree to extend the date, prior to which the minimum
amount of eight (8) million Units in the capital of Mexoro (the “Minimum Investment”) must be
subscribed for by Paramount, from June 23, 2008 to July 21, 2008. As a result,
the parties further agree that the references to June 23, 2008 under the
headings “Private
Placement”, “Convertible Debenture”,
“Closing and Conditions of
Closing”, “No
Negotiations with Other Parties” and “Termination” in the Letter
of Intent are hereby extended to July 21, 2008.
   
  
 2.           Convertible
Debenture. The parties agree that Mexoro may defer all interest payments
on the secured convertible debenture dated May 9, 2008 in the aggregate
principal amount of $500,000 (the “May Debenture”), issued
pursuant to the Letter of Intent, until the date of the Minimum Investment by
Paramount without penalty or default, provided that (i) all such accrued
interest shall become immediately payable upon the date of the Minimum
Investment, and (ii) in the event that the Letter of Intent, as amended, is
terminated, all accrued interest will become immediately payable to Paramount.
The parties further agree that Paramount shall loan the additional sum of
US$370,000 to Mexoro on or before June 21, 2008 to be secured by a one year
convertible debenture (the “June Debenture”) bearing
interest at 8% and to be secured by all of the assets of Mexoro and its
subsidiaries including Sunburst Mining de Mexico S.A. de C.V. Paramount shall
have the right to convert the aggregate principal amount of $370,000 of the June
Debenture to 740,000 Units of Mexoro on the same terms and conditions as the May
Debenture. Paramount agrees that payment of interest on the June Debenture shall
be deferred until July 21, 2008, provided that (i) all such accrued interest
shall become immediately payable on July 21, 2008, and (ii) in the event that
the Letter of Intent, as amended, is terminated, all accrued interest will
become immediately payable to Paramount.
 
 3.           Registration
Rights. The parties agree that Mexoro will use its best efforts to file
and have declared effective a registration statement with the Securities and
Exchange Commission pursuant to the Securities Act of 1933, with
respect to all shares of common stock of Mexoro issued and issuable to Paramount
pursuant to the May Debenture, the June Debenture and the private placement of
Units pursuant to the Letter of Intent, as amended, within six (6) months of the
date of the Minimum Investment, all subject to the terms and conditions of a
registration rights agreement, in a form satisfactory to Paramount, to be
entered into with Paramount on the date of the Minimum Investment.
 
 4.           Future
Financings.Paramount will be
provided a  right of first refusal for a period of 4 years from the
date hereof on all future financings of Mexoro whether by way of loan or share
subscription subject to 14 days written notice by Mexoro to Paramount with 90
days to close save and except for the current debt restructuring which includes
the settlement of $1.5 million of debt by way of issuance of equity units priced
at $0.50 USD per unit.  Each unit comprised of 1 share plus 1/2 common
share purchase warrant.  One full warrant is exerciseable at
$0.75.  This right of first refusal is only provided if Paramount
meets the minimum subscription of 8 million Units ($4 million).  In
the event that Paramount agrees to additional financing and fails to complete in
the 90 day time period, then Paramount shall forfeit its right of first refusal
on any subsequent financing.
  
 Except as
amended to reflect the above, the Letter of Intent remains in full force and
effect in accordance with its terms.
  The
parties acknowledge and agree that this Amendment is subject to review and
approval by the Board of Directors of Paramount.
  This
Amendment may be executed in any number of counterparts, all of which taken
together will be deemed to constitute one and the same instrument. This
Amendment may be signed and delivered by facsimile and same shall constitute
effective execution of the document.
   
   To
confirm this Amendment, please sign the enclosed duplicate copy where indicated
below and return it to Paramount within three (3) business days of the date of
receipt, or at that time the proposal set out above will expire
automatically.
  Yours
very truly,
  PARAMOUNT
GOLD AND SILVER CORP.
  
  Per:
 Christopher Crupi
 President and CEO
 
  Phone:  613-226-9881   346
Waverley Street, Ottawa, Ontario Canada  K2P
0W5   Fax:  613-226-5106
  
 * * * *
*
  This
Amendment, together with the Letter of Intent, reflects accurately the parties’
understanding and agreement with respect to the matters set out
above.
  
  MEXORO
MINERALS
LTD.                                                                                                SUNBURST
DE MEXICO S.A. DE C.V.
  
  Per:                            Per:
 Steven A.
Sanders, Director           Steven A. Sanders,
Assistant Secretary