The Santa Gertrudis property is located in the historic Magdalena gold and silver district that is currently the mining centre for several 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.
As at December 31, 2022, the Santa Gertrudis project hosts open-pit indicated mineral resources of 17.6 million tonnes grading 0.91 g/t gold (516,000 contained ounces of gold) and 3.7 g/t silver (2.1 million ounces of silver) and inferred mineral resources of 11.2 million tonnes grading 1.28 g/t gold (460,000 contained ounces of gold) and 2.1 g/t silver (745,000 ounces of silver), plus underground inferred mineral resources of 9.1 million tonnes grading 3.4 g/t gold (1.0 million contained ounces of gold) and 23.3 g/t silver (6.8 million ounces of silver).
During the first half of 2022, infill drilling at Santa Gertrudis totaled 160 holes (14,712 metres) and exploration drilling totaled 56 holes (26,780 metres). The infill drilling targeted shallow oxide mineralization in several deposits: Zona Central, Corridor Corral, Escondida, Greta and Cristina to advance scenarios to initiate mining in the oxide mineralization. The exploration drilling continued on several deposits including: Santa Teresa, where shallow oxide mineralization continued to grow; Amelia, where exploration in the eastern, western and deep fringes of the deposit continued; and the shallow Toro, Centauro and Bertha deposits elsewhere on the property, where exploration continued to investigate for a high-grade feeder system at depth.
Amelia is one of three deposits that comprise the Trinidad Trend and is the site of a previously operating open-pit gold mine. High-grade gold mineralization can be found in multiple parallel structures that commonly correspond to lithological contacts. The Amelia deposit strikes east-west for a length of approximately 900 metres and dips steeply to the north. Most of the open pit (oxide) material lies between surface and 140 metres depth, while the underground mineral resource below the open-pit mineral resource has been extended to a depth of approximately 700 metres.
As of December 31, 2020, the underground inferred mineral resource at Amelia totalled 785,300 ounces of gold and 6.2 million ounces of silver in sulphide (6.4 million tonnes grading 3.84 g/t gold and 30.8 g/t silver) and 93,700 ounces of gold and 220,000 ounces of silver in oxide (1.6 million tonnes grading 1.8 g/t gold and 4.3 g/t silver). The year-end 2022 mineral resources at Amelia are included in the overall mineral resource estimate at Santa Gertrudis.
The Espiritu Santo zone, discovered in 2019 at a location 500 metres east-southeast of Amelia, includes high-grade gold and silver mineralized structures at shallow depth.
The Santa Teresa zone contains a small historical pit located 3.2 km southwest of the Amelia deposit. As at December 31, 2021, the Santa Teresa oxide deposit was estimated to have an initial inferred mineral resource of 2.0 million tonnes grading 1.04 g/t gold (65,900 ounces of gold). Year-end 2022 mineral resources for Santa Teresa are included in the overall open-pit mineral resources at Santa Gertrudis.
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.
Geology & Mineralization
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.
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
At the Santa Gertrudis project in 2022, the Company had budgeted approximately $13.9 million for 43,150 metres of drilling, including 16,500 metres of infill drilling in the Cristina deposit and the series of deposits in the Zona Central trend as well as 26,650 metres of exploration drilling in several deposits including Amelia and Santa Teresa with a focus on growing mineral resources.