Santana Gold Project Maiden Resource Estimate
TORONTO - Minera Alamos Inc. reported on an independent estimate of the Mineral Resources currently outlined at the Santana gold project in Sonora, Mexico. The Resource Estimate was prepared in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects (NI 43-101).
"This maiden resource covers just the development zones in the immediate area of the current Santana mine operations and is a major step in highlighting the robust resource data and metallurgical input that provided the Company with comfort in developing our first low capital mine. The next open pit in the development plans for the Project, the Nicho main zone, is largely drilled off in sufficient detail for the estimation of measured and indicated resources with a grade and strip (waste: mineralization) ratio that we expect to provide meaningful low-cost production gold ounces for the next 5-6 years as the rest of the property is explored and better understood," stated Darren Koningen, CEO. "Notable nearby targets such as Benjamin which are outside of our current operations area have shown some excellent potential but will require more preliminary exploration and additional drilling to properly understand mineralization controls, grade distribution and tonnage. Ultimately, this current resource statement is just the first, conservative iteration of the geological potential across the broader Santana property with a goal of the current starter mine being a source of organic funding to prove up the greater potential of the area."
Mineralization in the Santana Project area is of the intrusive-related gold (Au-Ag-Cu-W) type and is associated with calc-alkaline-oxidized intrusive centres. Gold is hosted by hydrothermal breccias and their causative inter-mineral dykes and stocks and can form important mining districts with clusters of deposits. The intense alteration associated with the mineralization is linked to the emplacement of hydrothermal breccias which are in general sub-vertical pipe-like structures and typically a few hundred meters in diameter.
Locally, mineralization at the Santana Project occurs within breccias that have a jigsaw-type texture. These breccias typically comprise angular elongated fragments that have a preferential sub-vertical orientation. Review of core and outcrop indicates that these fragments did not undergo large displacements or rotations, which left open spaces between them that were subsequently infilled by gold-bearing hydrothermal minerals. The breccias are principally clast-supported and monomictic, and the presence of gold mineralization is directly related to the areas dominated by the breccia intervals.
In the case of Santana, there appears to be a cluster of potential gold-bearing deposits that conform to the description above within an area surrounding the main Nicho complex that is the subject of the current gold resource estimate. Further work is planned to properly understand the nature and size of these important targets and to delineate additional mineralization that could allow for prolonged or expanded project operations beyond what has been identified to date.
The majority of the Nicho gold mineralization that serves as the basis of the current resource estimate is located within an andesitic breccia zone above the deeper quartz-feldspar porphyry intrusive. Mineralization is generally well disseminated throughout the overall host rock volume with small scale enrichment in the fractures between the breccia matrix fragments.
Overall copper content in the mineralization is generally low and leaching results from ongoing operations at the Project indicate that its presence is manageable using free cyanide level-control in the leach solutions, with little impact on overall gold recoveries. The Nicho Norte mineralized material which was the primary source of past test leaching (2017-2019) and recent operations at the Project responds positively to gold cyanidation. Residual gold levels following these heap leaching activities typically approach levels of approximately 0.1 g/t Au. At mined head grades of 0.6 g/t Au to 0.7 g/t Au this equates to gold overall recoveries in the range of 80%. Leach kinetics are rapid for particle sizes up to approximately 1" (30-45 days or less). Although a reduction in kinetics appears at sizes greater than 1", ultimate gold recoveries at the end of the extended leach period were similar to those experienced with the finer-sized material.
Although more data is available for material from the Nicho Norte satellite deposit, comparative studies looking at test samples from the Nicho main deposit appear to exhibit similar results and additional work is ongoing. Recently tested samples of weathered material from upper zones in the deposit exhibited recoveries in line with the Nicho Norte material described above. Leach tests completed on samples of "worst case" fresh sulphide material from deeper in the Nicho deposit exhibited acceptable gold recoveries approaching 70% at crush sizes of <1/2" (coarsest size used for initial screening tests). Additional testwork is underway to more fully understand the overall gold recovery versus particle size relationships throughout the deposit due to variations in sulphide levels and weathering.
The report recommends that additional diamond drill holes, on approximately 25 m centres be drilled at the Benjamin Zone to further understand the distribution of gold mineralization within the zone and to look at opportunities to expand the size of the currently delineated mineralized area. The Company is currently planning to add approximately 10-12 more drill holes to those already drilled this year at Benjamin as a priority.
Additional recommendations include: Further review of the additional mineralized breccia targets which have been identified by the Company in the areas surrounding the Nicho complex (Goldridge, Zata, Bufita and East zones) area in order to prioritize the next phases of follow-up resource definition drilling A continuation of effective surface sampling activities with a focus on new areas that show similar mineralization characteristics as the Nicho and Nicho Norte zones; Geophysical studies targeting blind targets that have similar signatures as those observed over the known Nicho and Nicho Norte gold-bearing breccia zones; and Additional metallurgical studies (particularly crushing optimization studies) aimed at improving the overall understanding of variations in parameters such as leachability, recoveries and reagent consumptions for newly delineated zones of mineralization.