The Guapinol low-sulphidation epithermal vein trend is located in the northeastern portion of the Borosi Concessions and is part of the Eastern Borosi Project that also includes the Riscos de Oro and La Luna gold-silver deposits as well as additional targets at California, Blag and La Sorpresa. Calibre and IAMGOLD entered into an option agreement dated May 26, 2014 whereby IAMGOLD can earn a 51% interest in the Eastern Borosi Gold-Silver Project consisting of 176 km2 within the Borosi Concessions, Northeast Nicaragua, by incurring US$5 million in exploration expenditures and making US$450,000 in payments to Calibre by May 26, 2017. The total potential investment by IAMGOLD to earn a 70% interest in the Eastern Borosi Project is US$10.9 million. The Eastern Borosi Project hosts gold-silver resources in two deposits and a series of well-defined low sulphidation epithermal gold-silver targets.
The Guapinol trend is comparable in geology, mineralization, structure and size to the nearby producing Bonanza Camp (past production of ~2.8 Moz gold) and consists of a series of northeast oriented, sub-parallel veins that are defined by both anomalous gold-silver surface geochemistry and active artisanal mining pits (see photos below). The veins stretch over a strike length of 10 kilometres from Guapinol in the south, to the La Sorpresa target in the north, and are hosted within the same interbedded andesite volcanic sequence as the Riscos de Oro deposit.
Previous work at Guapinol has included: mapping, geophysics, geochemistry, trenching and minor drilling (Rosario 1975-77), which has identified multiple near surface targets that are ready for drill testing. Grab rock samples collected at Guapinol have returned values of 18.1 g/t gold and 13.1 g/t gold, while channel samples have returned strongly anomalous gold values up to 43.9 g/t/0.5m. At the California target located approximately 3 kilometres along strike from Guapinol samples of 21.9 g/t gold and 9.5 g/t gold have been returned; finally samples collected at La Sorpresa located 8.5 kilometres along strike returned grab samples of 42.5 g/t gold, 20.6 g/t gold, 17.1 g/t gold and 2,457 g/t silver, 1,387 g/t silver.
Drilling in 2014 and 2015 at Guapinol has identified a series of high grade gold-silver zones with intercepts including; 12.90 metres grading 8.73 g/t Au and 11.48 g/t Ag (Vancouver Vein), 6.03 metres grading 14.39 g/t Au and 14.41 g/t Ag (Guapinol Vein), 4.81 metres grading 25.66 g/t Au and 35.19 g/t Ag (Guapinol Vein), 1.00 metres grading 39.90 g/t Au and 132.00 g/t Ag (Guapinol Vein), 5.07 metres grading 13.44 g/t Au and 14.49 g/t Ag (Guapinol Vein) and 0.50 metres grading 19.20 g/t Au and 16.20 g/t Ag (California Vein). Nine kilometres to the north, and along trend from Guapinol, drilling at the La Sorpresa Target has discovered three gold-silver mineralized shoots with intercepts including; 4.10 m grading 8.93 g/t Gold and 57.4 g/t Silver (Cadillac), 1.40 m grading 5.71 g/t Gold and 15.7 g/t Silver (Jaguar), 1.40 m grading 9.70 g/t Gold and 98.0 g/t Silver (Cadillac), and 3.17 m grading 2.41 g/t Gold and 32.9 g/t Silver (Mercedes). Mapping by Calibre in the La Sorpresa area identified up to five veins with a cumulative strike length of 5.8 km with drilling to date in 2015 testing 1.1 km of four closely spaced veins at La Sorpresa; Mercedes, Cadillac, Lincoln, and Jaguar.