The Taguas Heap Leach Project is 100% owned by Orvana Argentina, S.A., a wholly-owned subsidiary of Orvana Minerals Corp.
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Summary:
The Taguas Property is host to a high-sulfidation epithermal gold-silver system hosted in altered tertiary age rhyolite volcaniclastic rocks. Supergene-oxidized gold-silver mineralization occurs on the south half of the Property. The oxide gold-silver mineralization consists of sub-vertical, northeast striking mineralized structures in an envelope of lower grade mineralization. The high grade zones consist of relatively continuous mineralization with gold grades ranging from 0.2 g/t Au to over 4.0 g/t Au and 10 g/t Ag to over 50 g/t Ag. Oxidation extends from surface to approximately 100m – 200m below surface.
Taguas consists of three gold-silver deposits:
• Leonor Vein at Cerro Silla Sur;
• Campamento Vein at Cerro Campamento;
• The gold-silver mineralization at Cerros Taguas.
The present PEA refers only to this oxidized gold-silver mineralization occurring near surface in Cerros Taguas.
Cerro Silla Sur
Cerro Silla Sur contains a northeast trending and steeply dipping (to the northwest) quartz-pyrite-enargite vein called Leonor. The central portion of the Leonor vein has returned grades of 7 to 42 g/t gold, up to 330 g/t silver and 0.1 to 5 % copper over drill intersections of less than 1 m to 7 m (Hedenquist, 2012). The mineralogical characteristics of the Leonor Vein are consistent with it being of the intermediatesulfidation type as evidenced by increasing amounts of chalcopyrite relative to enargite. Such intermediate-sulfidation veins typify the peripheral portions of high-sulfidation systems, and the elevated zinc and lead contents of Leonor lend support for cooler conditions of formation (Sillitoe, 2011).
Cerro Campamento
The mineralogical characteristics of the Campamento Vein are more consistent with it being of the high-sulfidation type as evidenced by the predominance of enargite over chalcopyrite. The Campamento vein has returned drill intersections 1-3m wide with 5- 35 g/t gold over a vertical interval of at least 100m (Hedenquist, 2012). The uppermost 100 meters of the Campamento vein usually contain only a few percent pyrite and enargite but often contain bonanza grade gold. Sillitoe (2011) proposed that the sulfide deficiency is a hypogene feature, and not the result of supergene oxidation. However, other geologists (e.g. Stewart, 2008; Kowalik, 2015 and 2017) believe that the sulfide and thereby copper deficiency but gold enrichment in the upper parts of the Campamento vein are due to supergene oxidation effects, depleting mobile copper and enriching less mobile gold. If so, the supergene zone should be transitional downwards into veins of massive sulfides, predominantly enargite with lesser pyrite. According to Hedenquist (2012), the amount of enargite in the Campamento vein does increase markedly with depth.
The mineralization in the upper 100 m to 200 m at Cerros Taguas, however, is markedly different from the mineralization at Campamento and Leonor. The mineralization at Cerros Taguas is not a single large vein like is mostly Leonor and Campamento but the product of very numerous small veins. Hedenquist (2012) proposed that Cerros Taguas may be a hydrothermal breccia bordering a felsic flow-dome intrusive. However, the purported intrusive flow dome contains rounded quartz eyes which may be more indicative of a tuff.
Cerros Taguas
The gold-silver mineralization intersected to date is hosted by lithic tuffs with higher grade zones controlled by northeast-trending siliceous structures. Based on underground mapping and sampling on the 4200 level at Cerro Taguas Norte and Cerro Taguas Sur, and drill intercepts, six high-grade domains were modelled as solid vein wireframes. An additional three high-grade domains, located beyond the underground exploration development, were interpreted based on drill intercepts.
The high-grade domains are sub-vertical and strike 230° to 250°. The true width of the high-grade domain’s ranges from 1.0 m to over 8.0 m and have lengths that range from 40 m to over 500 m and depths extending to 236 m below surface.
Mineralization at Taguas has the following characteristics that are consistent with the supergene-oxidized high-sulfidation deposit model:
• Near surface emplacement, hosted within Cenozoic aged volcanic units;
• Strong advanced argillic quartz-alunite alteration and saline fluid inclusions with high homogenization temperatures which indicates an acidic, magmatic fluid source
• Gold-silver mineralization in quartz-sulfide veins hosted in volcanic rocks and volcanic breccias
• The presence of jasperoids and clearly visible Fe-oxides at surface identify the supergene oxide zone.