Magdalena is an old gold and silver district that is currently the mining centre for five active mines and developments. The Santa Gertrudis property was the site of historic heap-leach operations that produced approximately 565,000 ounces of gold between 1991 and 2000. Substantial surface infrastructure is already in place on the property including pre-stripped pits, haul roads, water sources and buildings.
Drill programs by the Company in 2018 and 2019 at Santa Gertrudis have led to the declaration of initial open-pit indicated mineral resources of 5.1 million tonnes grading 0.64 g/t gold (104,000 ounces of gold) as well as inferred open-pit and underground mineral resources of 22.1 million tonnes grading 1.64 g/t gold (1.2 million ounces of gold) as of December 31, 2019.
In the northern portion of the Santa Gertrudis property, the high-grade Amelia deposit continues to grow, with exploration drilling in 2019 extending the Amelia ore shoot to 677 metres below surface. The updated inferred mineral resource at Amelia is 70,000 ounces of gold (1.6 million tonnes grading 1.38 g/t gold) in oxides at open pit depth, as well as an initial underground inferred mineral resource of 451,000 ounces of gold (3.1 million tonnes grading 4.58 g/t gold) in the high-grade sulphide material, as of December 31, 2019.
The 2019 Espiritu Santo discovery, 500 metres east-southeast of Amelia, includes high-grade gold and silver mineralized structures at shallow depth.
The Company is currently evaluating a potential production scenario at Santa Gertrudis that utilizes a heap leach for lower-grade mineralization and a small mill facility to process higher-grade ore. The Company believes that the Santa Gertrudis project has the potential to be a similar size operation to La India.
Geology
Northern Sonora has three northwest-trending mineralization corridors, which each have distinctive regional geological features. Santa Gertrudis covers a potential strike length of 25 km of the favourable Cretaceous-age intra-caldera sedimentary belt.
Mineralization
Three corridors with favourable geological formations have been identified on the property, with a potential strike length of 18 km. Within the corridors there are nine mineralized zones with multiple deposits; the mineralized deposits form trends that are hosted mainly by units within the sedimentary Morita, Mural and Cintura formations. Limited drilling has been completed between the deposits.
There appear to be three types of gold-silver mineralization (oxide, transitional and sulphide) at Santa Gertrudis. There is stratabound replacement mineralization in calcareous siltstone or on the margins of limestone. In addition, the Company's prospecting has identified high-grade mineralization along northeast-striking fractures that crosscut the stratigraphy and that appear to be important mineralization conduits.
Exploration
The 2019 exploration program at Santa Gertrudis totaled 143 holes (19,352 metres in Amelia and 23,426 metres in the rest of the project), compared with an initial budget of 29,000 metres of drilling. The 2020 exploration program at Santa Gertrudis will focus on expanding the current mineral resources and testing new targets.