Calibre Discovers New Porphyry and Skarn-Style Mineralization at La Virgen and Montes de Oro Targets, Borosi Concessions, Nicaragua

VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 03/25/13 -- Calibre Mining Corp. (TSX VENTURE: CXB) (the "Company" or "Calibre") is pleased to provide an update on the Company's exploration activities and recent discoveries at the La Virgen and Montes de Oro targets on the Borosi Concessions, northeast Nicaragua. Calibre controls a 100% interest in 429 km2 of mineral concessions and additionally, Calibre has joint venture exploration programs underway with Alder Resources Ltd. on the 33.6 km2 Rosita gold-copper-silver project; and with B2Gold Corp. on 322.3 km2 of concessions which include the Primavera gold-copper porphyry discovery.

Highlights

--  Recent exploration in Calibre's 100% owned Siuna District has discovered
    new porphyry gold-copper and skarn-style mineralization at the La Virgen
    and Montes de Oro targets coincident with large gold-copper soil
    geochemical anomalies with a trench at Montes de Oro returning 9.0 m
    grading 10.76 g/t Au and 0.12% Cu and a trench at La Virgen assaying
    45.0 m grading 0.40 g/t Au and 0.19% Cu;
--  Calibre's 100% owned gold/silver resource in three deposits hosts a
    combined NI43-101 Inferred Resource at a 0.6 g/t AuEq cut-off of
    10,750,000 tonnes grading 3.06 g/t Au and 24.38 g/t Ag containing
    1,057,000 oz Au, 8,430,000 oz Ag (See Calibre News Release dated
    September 5, 2012 for more detail);
--  Calibre has recently outlined a highly anomalous trend between the 100%
    owned Guapinol and California zones where high-grade epithermal gold-
    silver mineralization is being targeted over a 3,000 m by 500 m area in
    a series of seven closely spaced structures with surface grab rock
    assays including: 3.2 g/t Au, 21.9 g/t Au, and 9.5 g/t Au;
--  Historic drilling at Calibre's 100% owned Guapinol zone tested
    epithermal gold-silver mineralization over a 150 m strike length and to
    a depth of only 80 m with highlights including: 1.84 m grading 2.33 g/t
    Au and 276.48 g/t Ag and 3.10 m grading 13.08 g/t Au and 10.02 g/t Ag;
--  At the Primavera gold-copper porphyry project (B2Gold 51%, Calibre 49%)
    the current work program is designed to identify the faulted off
    extensions to the high grade gold-copper mineralization intersected in
    the central portion of the Primavera Zone (ie. DDH PR-12-016 - 201.35 m
    grading 0.77 g/t Au, 0.36% Cu). B2Gold has completed a series of
    exploration pits to the north and northwest of the existing drilling and
    assays results are pending;
--  At the formally producing Santa Rita copper/gold mine Calibre optionee
    Alder Resources Ltd has recently discovered high grade copper-gold-
    silver supergene mineralization at Tipispan that includes trenches
    assaying: 7.48% Cu, 2.36 g/t Au and 316.13 g/t Ag over 6.5 m and 5.21%
    Cu, 4.4 g/t Au and 144.01 g/t Ag over 12.1 m.

President and CEO, Greg Smith stated, "Our exploration programs on the Borosi Concessions within Nicaragua's Mining Triangle continue to prove that this highly prospective mining district remains fertile ground for new porphyry, epithermal vein and skarn gold-copper-silver discoveries including extensions to previously indentified zones and new mineralized structures. With 2013 exploration programs continuing on Calibre's 100% owned concessions, the Primavera gold-copper porphyry JV with B2Gold and the Santa Rita Option with Alder Resources, Calibre is well positioned for additional discoveries in this under-explored gold-copper-silver district."

100% Calibre owned Concessions

Calibre's 100% owned concessions contain the Cerro Aeropuerto, La Luna and Riscos de Oro Gold-Silver Deposits that host a combined NI43-101 Inferred Resource at a 0.6 g/t AuEq cut-off of 10,750,000 tonnes grading 3.06 g/t Au and 24.38 g/t Ag containing 1,057,000 oz Au, 8,430,000 oz Ag (see News Release Sept. 5, 2012 for details). On-going exploration programs by Calibre continue to advance the Eastern Epithermal Camp and the Western Siuna Camp.

The Eastern Epithermal Gold-Silver District is in the north-eastern portion of the Borosi Concessions and contains the Riscos de Oro and La Luna gold-silver deposits. Recent work has concentrated on the newly acquired Guapinol - La Sorpresa Trend consisting of a series of anomalous zones, past producing pits, shallow shafts and existing small scale mining areas extending over eight kilometres. Results of this work have defined a northeast- trending, highly anomalous zone between Guapinol and California outlining a series of up to seven sub-parallel, closely-spaced, structures which provide an excellent near surface target three kilometres long and averaging 500 metres wide.

Historic drilling at Guapinol consisted of 16 diamond drill holes testing a single structure along 150 metres of strike length and down to a depth of approximately 80 vertical metres. Highlights include: G-4; 1.84 m @ 2.33 g/t Au and 276.48 g/t Ag, G-6; 1.52 m @ 28.87 g/t Au and 21.87 g/t Ag, G-8; 3.10 m @ 13.08 g/t Au and 10.02 g/t Ag, and G-11; 0.5 m @ 32.43 g/t Au and 103.15 g/t Ag (see News Release Nov. 27, 2012 for further details).

The current exploration program consists of detailed soil sampling and trenching. Recent grab samples at Guapinol include surface quartz vein material grading; 13.1 g/t Au, 18.8 g/t Au and 3.8 g/t Au, while at California three kilometres NE sampling has returned; 3.2 g/t Au, 21.9 g/t Au, and 9.5 g/t Au. Recent grab sampling of vein material at La Sorpresa (8.5 kilometres NE of Guapinol) has returned consistently anomalous results including; B13R3072 @ 14.2 g/t Au and greater than 100 g/t Ag, B13R3071 @ 17.1 g/t Au and 74.0 g/t Ag, B13R3068 @ 9.9 g/t Au and 66.9 g/t Ag, and B13R3080 @ 0.99 g/t Au and 12.2 g/t Ag.

The Siuna District is in the western portion of the Borosi Concessions. Exploration completed by Calibre has identified porphyry and skarn targets. The Siuna District is host to the historic La Luz mine which produced more than 2.5 million ounces of gold from open pit and several underground levels developed down to 450 metres below surface. The District also hosts the existing Cerro Aeropuerto Inferred resource containing 700,000 ounces of gold and 3.1M ounces of silver (6.05Mt @ 3.64 g/t Au and 16.2 g/t Ag), and the Cerro Potosi target. Calibre's exploration programs have concentrated on the northern extension of the mineralized belt 10 to 40 kilometres north of the La Luz mine. The two main targets Montes de Oro and La Virgen are defined by strong gold-copper soil anomalies which have now been tested by trenching.

The La Virgen prospect was defined through a combination of prospecting, stream sediment sampling and subsequent soil sampling that defined a broad Au-Cu-As anomaly over a 500 m x 1000 m area. The most anomalous results have been traced to a 200 m x 300 m area near the peak of Cerro La Virgen where a series of narrow northeast oriented diorite dikes (dipping steeply towards the southeast) cut siltstone units from the Todos Santos Formation. In trench exposures, the dikes range from 1.20 - 17.80 metres in width, are often strongly oxidized containing highly anomalous Au-Cu values, and are commonly located in close proximity to steeply dipping faults and shears. Propylitic style alteration and minor quartz veins are noted in the surrounding wall rocks, which can also contain anomalous Au-Cu values. A large diorite body, located to the south of this area, is believed to be the source of the dikes. Significant trench results from this area include: 45.00 m @ 0.40 g/t Au and 0.19% Cu including 9.00 m @ 1.39 g/t Au and 0.19% Cu (VTR12-001), 7.50 m @ 0.21 g/t Au and 0.12% Cu (VTR13-011), 3.80 m @ 0.77 g/t Au and 0.72% Cu (VTR13-012), 3.90 m @ 1.55 g/t Au and 0.14% Cu (VTR13-013) and 10.20 m @ 0.70 g/t Au and 0.11% Cu (VTR13-021).

The Montes de Oro prospect, located four kilometres to the northeast of La Virgen, was defined through prospecting and stream sediment sampling. A subsequent soil survey highlighted a strong coincident Au-As-Cu-Pb-Zn anomaly over a 400 m x 650 m area. Detailed mapping and excavation of trenches and pits has helped define an irregularly shaped diorite body which cuts northwest through the prospect area and intrudes porphyritic andesite and apparent rafts of siltstone and limestone from the Todos Santos Formation. A strong, steeply dipping northeast oriented fault system bounds the prospect to the south and appears to have concentrated fluids through the prospect area resulting in extensive propylitic and skarn style alteration, development of a 200 m x 500 m northeast oriented gossan zone, and areas of massive sulphides further towards the northwest. Work at the prospect is highlighted by trench MTR13-009 which intersected 9.00 m grading 10.76 g/t Au, 0.12% Cu and greater than 1% Zn (assays pending) and by Pit 11 where a 2.00 m channel sample returned 27.18 g/t Au.

Primavera Gold-Copper Porphyry Project Update

B2Gold as operator of the Joint Venture continues to advance the Primavera gold-copper porphyry discovery. The current work program is designed to identify the faulted off extensions to the high grade gold-copper mineralization intersected in the central portion of the Primavera Zone. B2Gold has completed a series of pits to the north and northwest of the existing drilling and assays results are pending.

Santa Rita Option (Alder Resources) Update

Alder Resources continue to be active on the Santa Rita Project which includes the past producing Santa Rita copper-gold-silver open pit mine and a compliant inferred resource of 7.95 million tonnes grading 0.62% Cu, 0.46 g/t Au and 9.2 g/t Ag for the mine stockpiles (see news release dated May 9, 2012). Upcoming exploration will also be directed at further definition of the recently discovered high grade copper-gold-silver supergene enriched blanket at Tipispan that includes 7.48% Cu, 2.36 g/t Au and 316.13 g/t Ag over 6.5 metres and 5.21% Cu, 4.4 g/t Au and 144.01 g/t Ag over 12.1 metres in trenches.

Updated maps detailing the result of the current exploration programs will be posted on the Company's web site at www.calibremining.com. Mr. Gregory Smith, P.Geo, the President and CEO of the Company, is the Qualified Person as defined by NI 43-101, and is responsible for the accuracy of the technical data and information contained in this news release.

About Calibre Mining Corp.

Calibre Mining Corp. is a TSX Venture Exchange listed company (TSX VENTURE: 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 deposit, 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.

Greg Smith, P.Geo., President and CEO

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.

Contacts:

Calibre Mining Corp. - Vancouver, Canada

Mark Carruthers

604 681 9944
www.calibremining.com