Calibre Amends Terms of Borosi Gold-Copper Project Share Purchase Agreement With Yamana

May 10, 2012

Vancouver, British Columbia: Calibre Mining Corp. (TSX-V: CXB) (the "Company" or "Calibre") is pleased to announce that the Company has signed an amending agreement (the "Amending Agreement") with Yamana Gold Inc. (TSX: YRI, NYSE: AUY, LSE: YAU) ("Yamana") amending the Share Purchase Agreement dated July 21, 2009 between the parties. Pursuant to the Share Purchase Agreement Calibre acquired a 100% equity interest in Yamana (Nicaragua) Ltd, whose wholly owned subsidiary owns a 100% interest in the Borosi Gold-Copper project, consisting of a number of contiguous mining and exploration concessions located in northeast Nicaragua.

Douglas Forster, Chairman of Calibre commented: "We are pleased to have amended the Borosi gold-copper project acquisition agreement so that a contingent Bonus Payment to Yamana of up to $3.5 million is now eliminated. The amendments are also advantageous to Yamana in that their Bonus Warrants will immediately vest and, if exercised, would provide Yamana with potential additional capital gains while adding $2.5 million to Calibre's treasury."

Under the original Share Purchase Agreement Calibre previously issued 12 million common shares and paid $4.2 million in cash to Yamana. Also under the terms of the original Share Purchase Agreement Calibre would have been required to pay Yamana a bonus of $5 per ounce of newly reported gold equivalent as set out in any new NI 43-101 resource report of measured or indicated resources on the Borosi project (the "Bonus Payment"), to a maximum of $3.5 million, if such report was prepared within 5 years from closing. Calibre also issued 5 million warrants exercisable at $0.50 per share and 5 million warrants exercisable at $1.00 per share (collectively, the "Bonus Warrants"). The Bonus Warrants expire on July 21, 2014 and only vest and are exercisable if Calibre delineates at least 2.5 million NI 43-101 compliant ounces of gold equivalent in the measured and indicated categories for the Borosi project (the "Vesting Condition").

Under the terms of the Amending Agreement, Calibre is no longer required to pay the Bonus Payment and in return Calibre has agreed to apply to the TSX Venture Exchange for a re-pricing of the Bonus Warrants such that, upon acceptance by the TSX Venture Exchange, all Bonus Warrants shall be exercisable at $0.25 per share. In addition, Calibre has agreed to remove the Vesting Condition and all the Bonus Warrants shall be immediately exercisable.

About Calibre Mining Corp.
Calibre Mining Corp. is a TSX Venture Exchange listed company (TSX.V: CXB) that is focused on the acquisition, exploration and development of gold and silver deposits in Central America. The Company is focused on its 100% owned Riscos de Oro gold-silver project, the drilling program at the Primavera gold-copper project in conjunction with B2Gold Corp. and the drilling program on the Rosita copper-gold-silver project in conjunction with Alder Resources Ltd. Major shareholders of Calibre include gold producer B2Gold and investment fund Sun Valley Gold.

Calibre Mining Corp.

"Douglas Forster"

Douglas Forster, M.Sc., P.Geo.

For further information contact:
Mark Carruthers - Vancouver, Canada
604 681 9944

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.


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