Gold and Silver mineralization at the Nico project was first discovered by Mirasol geologists in 2004 while following up high priority targets from the company’s Santa Cruz generative program. In 2009, Coeur Mining who operated the adjacent high grade Martha Silver Mine at the time, signed a Joint Venture with Mirasol for Nico, completed one drilling program, then returned the project to Mirasol without any retained interest. In 2016, encouraged by an improving investment climate, Mirasol resumed activity at the project.
Since then, Mirasol’s exploration team has made exemplary advancements on the Nico Project. New claims were staked, covering potential extensions of the mineral trends, bringing the total area covered by the Nico project to 78,000 ha. Surface exploration has delineated significant geophysical anomalies. Systematic rock chip and float sampling have identified three new prospects (Aurora, Vittoria and Resolution named after the flagships of famous southern hemisphere explorers of the 15th to 17th centuries), returned “bonanza” grade silver - gold assays with peak grades (from rock chip sampling) yielding up to 35 g/t Au and up to 6,000 g/t Ag. Initial drill testing is planned for Q4 2018.
The Nico Project is situated in a logistically favorable setting in rolling hills at a modest elevation of approximately 600 m AMSL. The project is traversed by a well-maintained provincial gravel road. Nico is located 43 road km north of the Martha high grade silver mine, recently recommissioned by Hunt Mining, and 83 road km northwest of the Manantial Espejo Silver-Gold mine operated by Pan America Silver. Pan American plans to truck ores mined at COSE and Joaquin through Mirasol’s Nico Project properties to the Manantial Espejo mine facilities for processing. Nico is well-positioned to benefit from Pan American’s announced development and processing plans.
In February 2009, Mirasol joint ventured Nico to Coeur Mining (Coeur) who were at the time operating the bonanza grade Martha Silver-Gold mine in the area. Coeur completed one drilling program totalling 1,472 m in 11 shallow holes at Nico Main with best results of 8.25 m @ 0.43 g/t Au and 37 g/t Ag, including 1.25 m at 2.17 g/t Au and 197 g/t Ag. No follow-up drilling was undertaken and the project was returned to Mirasol.
In 2016, encouraged by an improving investment climate, Mirasol resumed activity at the project. To date, Mirasol has identified four prospects Aurora, Resolution, Vittoria and Endeavour where strongly anomalous to bonanza grade silver – gold assays have been returned from surface rock chip sampling and historic drill intersections at the Nico Project.
Mirasol interprets the Nico mineralization to potentially be an example of a silver - gold rich epithermal intermediate sulfidation precious metal system. This class of mineralization has produced multi-million-ounce high-grade silver - gold vein style ore bodies in Santa Cruz Province, including Cerro Moro (Yamana Gold) and San Jose (Hochschild Mining/McEwen Mining) mines, as well as smaller, bonanza-grade mines such as Martha (Hunt Mining).
The geological understanding emerging from the 2016-2018 exploration programs at the Nico Project suggests that mineralization is associated with a large rhyolitic flow dome and pyroclastic complex that overlies the regional rhyolite ignimbrites volcanics of the Chon Aike formation. At Nico, epithermal intermediate sulphidation vein-breccia mineralization is developed at several prospects both within the dome and pyroclastic complex and the underlying Chon Aike volcanics.
Reconnaissance mapping and sampling has led to the discovery of a new high-grade epithermal vein at the Resolution Prospect. The mineralization reports to oxidized veins and veinlets of grey chalcedonic silica with localized zones of banded saccharoidal silica and breccia textures hosted in dacitic subvolcanics.
Recent geological mapping, electrical geophysics, and rock chip and saw-cut channel assay results has outlined a target zone up to 2,100 m long and up to 230 m wide, that is considered prospective for epithermal Silver-Gold mineralization at Resolution. Mirasol is now undertaking an integrated analysis of this data to identify and prioritize targets for an initial shallow drill test of the Resolution prospect, anticipated for the 4th Quarter of calendar 2018.
Mirasol also collected outcrop saw-cut channel samples from 52 channel-sample lines which cross the Main and subsidiary structures of the Resolution prospect. The aim of this work was to test if this systematic sampling approach would confirm the presence of high grade mineralization identified in rock chip sampling, and to also test the grade of the Main Structure with locally developed “stringer” veinlet halos. A total of 25 saw-cut channel lines returned length-weighted assay intervals at ≥ 1.0 g/t AuEq60 cut off. Intersections typically ranged between 1.34 m at 155 g/t Ag and 0.04 g/t Au (2.6 g/t AuEq60), and 0.2 m at 579 g/t Ag and 4.57 g/t Au and (14.2 g/t AuEq60), with the highest grade intercept of 0.3 m at 950 g/t Ag and 4.27 g/t Au (20.1 g/t AuEq60).
The mineralized vein-breccia structures at Resolution are hosted within a porphyritic dacite unit delineated by geological mapping and by a + 600 m diameter resistivity anomaly in the Pole Dipole (PDP) electrical geophysical ground survey. The dacite dome may represent part of a larger area Jurassic-aged subvolcanic dome complex at the prospect. The prospect-scale structural setting, combined with brittle host rocks like the dacite dome, are conducive to development of down-dip and along strike “pinch and swell” veins typical of epithermal deposits. The PDP electrical geophysical survey recently reported defined a 1.4 km long, 8 to 25 millisecond chargeability anomaly, that in plan and section lies along the down-dip projection of the outcropping vein-breccias. These chargeability anomalies represent high priority targets for drill testing at the Resolution Trend.
Mapping and sampling completed at the Aurora Prospect have defined a principally north-south oriented, high grade, Gold-Silver mineralized trend of approximately 4 km by 2.1km from multiple oxidized vein and vein-breccia structures. This trend extends to the edge of post-mineral basalt cover to the north and south, suggesting the system may continue under cover and have a longer strike length than currently defined. As well, outcrop and sub-crop distribution of samples suggests the potential for adjacent parallel vein breccia trends in some areas of the prospect. These results were used to define nine priority target areas at Aurora (Ar1 to Ar9).
Prospecting and rock chip sampling at Target Ar1 was completed in June 2018, prior to the end of the field season. A total of 63 rock chip outcrop, subcrop and float samples were collected, defining new vein-breccia trends, that combined with previous sampling, suggest a total cumulative strike of mineralized structures in the Ar1 target of > 1,000 m in four trends. 55 of the 63 rock chip samples report to sub-cropping, vein-breccia trends estimated to be 0.1 to 0.35 m wide while the remaining 8 samples were of the altered wall rock. The 55 vein-breccia samples assayed an average of 4.03 g/t Au and 44.46 g/t Ag (4.8 g/t AuEq60), with a peak assay of 21.40 g/t Au and 454.1 g/t Ag (28.9 g/t AuEq60).
The true width of the vein-breccia zones at Aurora Target Ar1 is not known at this time due to the recessive weathering character of the vein-breccia mineralization; however, these results are considered encouraging, suggesting the presence of multiple high-grade Gold-Silver trends at this target, one of the nine targets in the larger Aurora prospect. Results to date suggest that the Aurora prospect is more gold-rich in comparison to the silver dominant Resolution prospect.
Mirasol in currently planning mapping, sampling and geophysical programs to systematically evaluate the nine exploration targets at Aurora. It is anticipated exploration will re-commence at Aurora during September 2018 (Southern Hemisphere Spring), with the aim of defining targets for potential drill testing later in the 2018-19 summer exploration season.
Vittoria Vein Trend
Recent reconnaissance exploration at Nico identified an additional new silver - gold prospect, the Vittoria Vein Trend, that to date has been traced over a 1.6 km strike length.
The Vittoria Vein Trend ranges from sub-meter to locally up to 10 m wide trend, characterized by multiple parallel 0.3-0.5m wide chalcedonic quartz vein outcrops and sub-cropping blocks, that have returned rock chip assays of up to 1.44 g/t Au and 174 g/t Ag from 129 samples.
The Endeavour Prospect was discovered in 2003. Surface work completed to date includes geological mapping, detailed ground geophysics (magnetics + gradient array IP survey), 209 rock chip samples with assays returning to 8.6 g/t Au and 324 g/t Ag, and 11 shallow diamond drill holes totaling 1,475m will best intersection 8.25m @ 0.43g/t Au and 37 g/t Ag including 1.25 m @ 2.25 g/t Au and 197 g/t Au.
To learn more about past and recent results and the exploration potential at Nico, see all Current and Historical News Releases.
Additional Explanatory Notes: * AuEq60 is the sum of the value of gold and silver in a given interval represented as a gold equivalent g/t value calculated via the formula: Au assay in g/t + (silver assay in g/t ÷ 60)