Eastern Borosi Gold-Silver Property

Calibre controls an undivided 100% interest in the Eastern Borosi Gold-Silver Property (the “Property” or “EBP”),  located in the northeastern Nicaragua a low-sulphidation, epithermal district that hosts numerous high-grade, gold-silver vein systems. The vein systems hosting the current 700,500 ounces of Inferred Resources at 4.9 g/t Au remain open to further expansion along with numerous undrilled targets. From 2014 to 2020, IAMGOLD Corporation (“IAMGOLD”) spent over US$10 million on the Property in order to earn a 70% interest in the Property. As of August 13, 2020, Calibre restructured the deal with IAMGOLD - see Calibre news release dated August 13, 2020 (click here).

Consideration for IAMGOLD’s 70% interest in the EBP includes (i) 2,253,961 common shares of Calibre (US$3 million), (ii) US$1 million in cash payable 12 months after the date of the acquisition agreement, and (iii) a 2.0% Net Smelter Return royalty (the “NSR Royalty”) on future production from the Property. Calibre has the right to purchase 1.0% of the NSR Royalty for US$2 million and a right of first refusal on the remaining 1.0% NSR Royalty.

The EBP is located approximately 400 km by road from the Company’s Libertad Complex, which has surplus processing capacity of approximately 1.5 million tonnes per annum.

Exploration to date on the Eastern Borosi Project has outlined several tens of kilometres of highly prospective mineralized structures located in an historic gold-silver mining district. Targets have been defined by surface soil and rock sampling, trenching and drilling.

Drilling completed between 2016 and 2018 on four earlier stage satellite targets (separate from the NI 43-101 Mineral Resources noted above) intercepted high-grade gold-silver mineralization demonstrating further exploration upside.  Highlights of drill results reported previously (see Calibre news releases dated September 15, 2016, February 1, 2018 and December 18, 2018) include:

  • Cadillac Zone:  2.6 metres Estimated True Width (“ETW”) averaging 8.93 g/t Au and 57.4 g/t Ag between 65.6 and 69.7 metres down-hole in drill hole LS15-008;
  • San Cristobal Zone:  5.7 metres ETW averaging 10.92 g/t Au and 859.0 g/t Ag between 87.8 and 95.9 metres down-hole in drill hole SC18-002;
  • Veta Loca Zone:  5.4 metres ETW averaging 10.15 g/t Au and 6.9 g/t Ag between 88.8 and 94.3 metres down-hole in drill hole GP16-046; and
  • La Luna South Zone:  12.7 metres ETW averaging 5.75 g/t Au and 34.3 g/t Ag between 53.0 and 68.9 metres down-hole in drill hole LL18-012.

EBP consists of 176 km2 of mineral concessions within the Company’s larger concession holdings in the prolific “Golden Triangle” region of northeast Nicaragua. The Property hosts gold-silver resources in multiple vein systems that comprise part of a larger district of epithermal style, gold-silver mineralization. 

Mineral resources have been defined in six vein systems that are exposed along an eight-by-ten kilometre structural trend that remains open to the northeast and southwest.  Calibre intends to (i) evaluate the potential to expand known resources where the vein systems remain open along strike and at depth, (ii) identify and test new vein systems along the structural trend, and (iii) evaluate the opportunity to leverage the resource potential of the Property as part of the Company’s ‘hub-and-spoke’ operating philosophy.   Click here to see Deposit Location Map.

Summary of INFERRED Mineral Resources – AS OF March 15, 2018
Eastern Borosi Project

Category Method/ Tonnage Grade Contained Grade Contained
  Vein (000’s) Au Gold Ag Silver
      (g/t) (ounces) (g/t) (ounces)
Inferred Underground          
  Blag 740 3.01 71,500 117 2,776,000
  East Dome 513 2.23 37,000 219 3,611,000
  Riscos de Oro 1,184 5.73 218,000 106 4,046,500
  Guapinol 612 12.74 250,500 12 243,000
  Vancouver 170 8.54 46,500 15 81,500
  Total 3,219 6.03 624,000 104 10,758,500
Inferred Open Pit          
  La Luna 1,199 1.98 76,500 16 601,000
Inferred Total
And Open Pit
4,418 4.93 700,500 80 11,359,500


  1. CIM (2014) definitions were followed for classification of Mineral Resources.
  2. Mineral Resources are estimated at a cut-off grade of 2.0 g/t AuEq for resources potentially mined by underground methods and 0.42 g/t AuEq for resources potentially mined by open-pit methods.
  3. Mineral Resources and gold-equivalent cut-off grades were estimated using long-term gold prices of US$1,500 per ounce and US$23 per ounce of silver. Gold equivalent cut-off values were calculated using the formula: AuEq (g/t) = Au (g/t) + Ag (g/t) / (101.8)
  4. A minimum mining width of 2.4 meters was used for underground and 3 metres for open-pits.
  5. Bulk density is 2.65 t/m3 for Blag, East Dome, Riscos De Oro and La Luna, and 2.60 t/m3 for Guapinol and Vancouver.
  6. East Dome is included in the Blag resource model and Vancouver is included in the Guapinol resource model.
  7. Numbers may not add due to rounding.
  8. Mineral Resources that are not Mineral Reserves do not have economic viability.
  9. For further details refer to ‘NI 43-101 Technical Report on the Eastern Borosi Project, Nicaragua’ dated May 11, 2018.

The Cadillac Zone is one of five defined epithermal vein structures in the La Sorpresa area located five kilometers north of the Blag Gold-Silver Zone.   Drill holes on the Cadillac Zone expanded on the success of the 2015 discovery hole (LS15-008) which intersected 2.6 metres ETW grading 8.93 g/t Au and 57.4 g/t Ag (see Calibre news release dated February 1, 2018).   Highlights include:

  • LS17-018: 2.6 metres ETW averaging 7.76 g/t Au and 179.3 g/t Ag between 121.7 and 125.8 meters down-hole;
  • LS17-020: 2.2 metres ETW averaging 7.48 g/t Au and 116.7 g/t Ag between 118.55 and 122.04 metres down-hole; and
  • LS17-022: 1.0 metres ETW averaging 16.7 g/t Au and 271.6 g/t Ag between 135.6 and 137.3 metres down-hole.  

Drilling along the Cadillac vein system has been completed along a 200 metre strike length to a vertical depth of 100 metres from surface. The vein system remains open along strike and down-dip.

The San Cristobal Zone is located approximately 2.5 kilometres northwest of the Blag and East Dome deposits. Details of the discovery intercept noted above include:

  • SC18-002: 5.7 metres ETW averaging 10.92 g/t Au and 859.0 g/t Ag between 87.8 and 95.9 metres down-hole, including 1.1 metres averaging 54.7 g/t Au and 3,957.0 g/t Ag between 94.3 and 95.9 metres down-hole.

The San Cristobal Zone has been traced on surface with rock and soil sampling for approximately two kilometres, with potential recognized for additional sub-parallel vein structures along the zone (see Calibre news release dated December 18, 2018).

The Veta Loca Zone is located 300 metres south of the Guapinol Gold-Silver Zone.  To date, 11 drill holes totaling 2,800 metres have confirmed the presence of at least three, closely spaced sub-parallel vein structures, testing them to a depth of 100 metres from surface. The Veta Loca zone remains open at depth.  Highlights include: 

  • GP16-046: 5.4 metres ETW grading 10.15 g/t Au and 6.9 g/t Ag between 88.8 and 94.3 metres down-hole; and
  • GP17-057: 6.3 metres ETW averaging 9.69 g/t Au and 2.9 g/t Ag between 33.7 and 41.2 metres down-hole.

Follow up drilling subsequent to the 2018 resource estimate was also carried out on the La Luna South gold-silver vein system. Highlights include:

  • LL18-012: 12.7 metres ETW averaging 5.75 g/t Au and 34.3 g/t Ag between 53.0 and 68.9 metres down-hole (including 4.7 metres ETW averaging 17.78 g/t Au and 32.5 g/t Ag).  

This hole represents the highest-grade mineralization encountered to date on the La Luna Zone.  Mineralization at La Luna remains open along strike and down dip (see Calibre news release dated September 5, 2018).

Eastern Borosi Property Map

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