The Curibaya property is comprised of approximately 16,800 hectares situated in a copper porphyry belt that hosts some of Peru’s largest porphyry deposits, including Freeport McMoRan’s Cerro Verde deposit, Southern Copper’s Cuajone and Toquepala deposits and Anglo American’s Quellaveco deposit. The project is the first major epithermal occurence in this belt, which covers the regional Incapuquio fault zone and subsidiary structures, which are interpreted as one of the fundamental controls for both epithermal and porphyry styles of mineralization within the region. Importantly, the licenses host a number of cross structures to the Incapuquio fault zone that are considered highly prospective. Initial surface sampling programs at Curibaya returned numerous high-grade samples of silver, gold and copper over a 4 kilometre (km) x 5 km alteration system. The 2021 maiden drill program has returned multiple significant intercepts, including 1.5 metres (m) of 1,129 g/t silver, 1.04 g/t Au in a larger interval of 7 m of 272 g/t Ag, 0.33 g/t Au and 1 m of 1,431 g/t Ag, 0.39 g/t Au within a broader interval of 1.5 m of 965 g/t Ag, 0.26 g/t Au.
The Curibaya project is located 48 km north-northeast of the provincial capital, Tacna, and is accessible by road in 1.5 hours.
World-Class Exploration Opportunity
2021 Maiden Drill Program Summary:
Drill hole 16 intercepted 1.5 m of 1,129 g/t Ag, 1.04 g/t Au in a larger interval of 7 m of 272 g/t Ag, 0.33 g/t Au on the Sambalay structural corridor. This drill hole targeted higher elevations of the intermediate sulphidation system than the majority of the holes drilled to date and is located on a two km corridor that extends toward the Cambaya target area, where the Company has seen the best channel sample results, including 20 m of 243 g/t Ag, 0.71 g/t Au, 11 m of 232 g/t Ag, 1.61 g/t Au, 9 m of 409 g/t Ag, 0.41 g/t Au, 2 m of 1,736.5 g/t Ag, 1.61 g/t Au, and 2 m of 1,074 g/t Ag, 0.53 g/t Au. Approximately 100 m north of hole 16, hole 15 intersected 4.5 m of 90 g/t Ag, 0.08 g/t Au along the same structural corridor, demonstrating continuity of mineralization over a 4.5 m to 7 m wide system of quartz-adularia veining. Geological mapping has demonstrated that the zones of quartz-adularia veining extend 1.4 km north of the Cambaya II target area. To date, four drill holes have been completed in the corridor, for a total of 1,251 m, over a strike length of 350 m and a vertical depth of 120 m below surface. Three of the four drill holes have intersected quartz adularia veins demonstrating the potential of this corridor. Further work will concentrate on identifying changes in vein orientations as a mechanism to focus high-grade along the structures.
Hole 6 targeted the Madre structure, which has emerged as the primary target structure on the project to-date, and intersected incl. 1 m of 1,431 g/t Ag, 0.39 g/t Au. Tier One’s technical team believes the results from hole 6 demonstrate the high-grade potential along the 1.4 km long Madre structure, as defined by mapping and remote sensing data.
Hole 9 drilled incl. 3 m of 350 g/t Ag, 0.47 g/t Au in a wider interval of 5.5 m of 201 g/t Ag, 0.27 g/t Au and was the first hole to target the Tipal structural corridor. This corridor is primarily defined by an airborne magnetics gradient that has a strike length of 2.5 km. The Tipal structural corridor represents the fourth corridor with confirmed silver-gold mineralization in the third dimension at Curibaya.
Drill holes 4 and 5 targeted the Sama and Sambalay structures, respectively, and both drill holes encountered significant silver mineralization in multiple parallel structures. Hole 5 is the second drill hole to test the 900 m long Sambalay structural corridor and intersected 1 m of 446 g/t Ag, 1.83 g/t Au.
Go to Nov. 18, 2021 news release for complete summary of results from drill holes 4-6.
Go to Jan. 24, 2022 news release for a complete summary of results from drill holes 7-11.
Go to Feb. 14, 2022 news release for a complete summary of results from drill holes 12-16.
CSAMT Results - Two Porphyry Copper Targets:
Recent geophysical survey results, combined with existing exploration data sets, have led to the identification of two porphyry copper targets underlying the silver-gold epithermal mineralization defined on surface at Curibaya (see Jan 30, 2023 news release). Tier One Silver completed a 42.7-line km Controlled-Source-Audio-Frequency Magnetotelluric (CSAMT) geophysical survey over the central portion of the Curibaya project in late 2022. CSAMT identified two sub-vertical, low resistivity anomalies (400 m x 400 m and 600 m x 500 m) that are interpreted to be associated with a large-scale hydrothermal alteration system. These new data sets were integrated into the exploration model, building on previous geophysical, geochemical and geological data sets, to generate targets for the Company’s next drill program at the project.
2021 Channel sampling from the Cambaya target at the Curibaya project included highlights of 20 m of 242.7 g/t Ag, 0.71 g/t Au, 11 m of 232.1 g/t Ag, 1.61 g/t Au, 9 m of 409 g/t Ag, 0.41 g/t Au, 2 m of 1,736.5 g/t Ag, 1.61 g/t Au and 2 m of 1,074 g/t Ag, 0.53 g/t Au (true width of channel samples unknown). Channel samples were oriented perpendicular to veins and structures, when possible, as mapped in the field.
2022 channel sampling results included 4.5 m of 408.2 g/t Ag and 1.48 g/t Au, including 1 m of 1,768.0 g/t Ag and 6.33 g/t Au, in 22CRT-080, 8 m of 349.1 g/t Ag and 0.46 g/t Au, including 1 m of 2,680.0 g/t Ag and 3.14 g/t Au, in 21CRT-56 and 2.5 m of 136.4 g/t Ag and 0.82 g/t Au, including 0.5 m of 568.0 g/t Ag and 3.37 g/t Au, in 22CRT-101. Importantly, arsenic values were generally highly elevated across the Cambaya target area, indicating to the technical team that the target is at the top of the epithermal system, with the precious metals window being preserved at shallow depths.
Rock grab sampling has returned grades of up to 298,000 g/t silver and 934 g/t gold, with samples spread across a 4 x 5 km alteration system. Rock grab sample highlights are shown in the table to the right using cut-off grades of 500 g/t Ag and 2 g/t Au.
Additional Channel Sampling Highlights:
Initial channel sample highlights from the Curibaya project included 2 m of 6,253.2 g/t Ag, 0.36 g/t Au, 6 m of 354.2 g/t Ag, 0.62 g/t Au and 12 m of 174.6 g/t Ag, 0.40 g/t Au. These results demonstrate both high-grade vein and disseminated styles of mineralization within the 4 km by 5 km alteration system that currently defines the mineralized system at the project. The ongoing drill program at the project is targeting both styles of mineralization based on extensive geologic mapping, geophysical resistivity and chargeability signatures where steeply dipping feeder structures and horizontal bodies of mineralization occur. The channel samples being reported are situated within several sub-horizontal mineralized bodies that have been mapped on surface within three distinct units within the upper Toquepala volcanic sequence. Importantly, Tier One’s technical team believes there is an opportunity to find additional sub-horizontal bodies of mineralization emanating from high angle feeder structures both within the poorly exposed lower Toquepala volcanic sequence and underlying sedimentary basement stratigraphy. Collectively, the surface channel sampling results demonstrate that cohesive bodies of mineralization are present on the project over considerable widths and that the drill targets of the shallow flat lying chargeability anomalies under the channel samples have the potential to yield significant zones of precious metal mineralization.
Tier One has identified the age of mineralization at Curibaya to be Paleocene, ranging from 55 to 61 million years. This is equivalent to several world-class deposits in the southern Peru porphyry belt, including Quellaveco (Anglo American), Toquepala (Southern Copper Corp.) and Cuajone (Southern Copper Corp.). Tier One's technical team believes the Paleocene age date of the mineralization, along with the large precious metal budget observed within high-grade veins over a 4 km x 5 km alteration system, support the potential for a world-class discovery at the Curibaya project.
At this early stage, the Company’s technical team believes there are both precious metal intermediate sulphidation epithermal and copper porphyry targets.
Tier One Silver was spun out from Auryn Resources in October 2020, therefore inheriting ownership of the Curibaya project and relating obligations. Auryn had a 100% interest in the Curibaya concession (acquired in 2015) and the Sambalay and Salvador concessions (acquired in 2019). The Sambalay and Salvador concessions are subject to certain historical NSR royalties.
Under the Mining Concessions Transfer Agreement (the “Transfer Agreement”) entered with Wild Acre Metals (Peru) S.A.C. dated August 2, 2019, the Company paid US$250,000 for the transfer of the Sambalay and Salvador concessions, in favor of the Company, upon recording of the Transfer Agreement with the Peruvian Public Registry. The Sambalay concessions are subject to a 1.5% NSR royalty in favor of each of Teck Peru S.A.C. (“Teck”) and Compania de Exploraciones Orion S.A. (“Orion”). One third, or 0.5%, of the Teck NSR royalty is buyable for US$1.0 million. The Salvador concessions are subject to a 2% NSR royalty and a US$2.0 million production payment, payable at the time a production decision is made, and to secure payment of such consideration a legal mortgage in favor of Teck is recorded in the registry files of the Salvador concessions.
The Company has previously disclosed estimated silver equivalent grades where drill core or channel samples contained more than one mineral in addition to silver. These silver equivalent grade estimates were not adjusted downwards to reflect the fact that metal mining and processing always results in a loss of metal content from in-situ grades. The previously disclosed silver grades while indicative of the presence of metal mineralization, cannot be relied upon for any kind of economic assessment of the mineralization until metallurgical recovery studies have been completed and a range of likely recovery percentages established and applied to the various metals in the mineralization. The Company’s disclosure policy going forward is to disclose the grade of each metal separately when more than one metal is contained in an assayed sample.
Geologic Context of Vein Mineralization:
The high-grade precious metal veins sampled to-date on the project range in width from five centimeters to one meter and are situated in north – south corridors radiating from the identified flow dome complexes. The sampled veins are primarily situated in the overlying volcanic sequence above the flow dome complexes and provide a good indication of the metal budget; however, are not the target themselves. The Company believes the veins represent a high-level dispersion of a robust precious metal system that is situated along the margins of the dome complexes at shallow depths. These flow dome complexes provide a geological mechanism to concentrate fluid flow where potential geologic targets include high-grade veins, vein stockwork zones and silicified hydrothermal breccias that would be situated along the margins of the domes.
Age Dating, 2020
A total of four samples of altered volcanic rocks were collected for Ar-Ar geochronology analysis. Samples were sent to Pacific Centre for Isotopic and Geochemical Research, University of British Columbia, in Vancouver, Canada. They were analyzed through neutron irradiation at McMaster Nuclear Reactor in Hamilton, Ontario, and a VG5400 mass spectrometry. The best statistically justified plateau and plateau ages picked. Two out of four samples had isochrons sufficient for plateau age determination.
PERU Rocks Q4 2020
Approximately 2-3kg of material was collected for analysis and sent to ALS Lab in Arequipa, Peru for preparation and then to Lima, Peru for analysis. All samples are assayed using 30g nominal weight fire assay with ICP finish (Au-ICP21) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where ICP21 results were > 3 g/t Au the assay were repeated with 30g nominal weight fire assay with gravimetric finish (Au-GRA21). Where MS61 results were greater or near 10,000 ppm Cu, 10,000ppm Pb or 100ppm Ag the assay were repeated with ore grade four acid digest method (Cu,Pb,Ag-OG62). Where OG62 results were greater or near 1500ppm Ag the assay were repeated with 30g nominal weight fire assay with gravimetric finish (Ag-GRA21). Where Ag-GRA21 results were greater or near 10,000ppm Ag the assay were repeated with fire assay with gravimetric finish for concentrate (Ag-CON01). QA/QC programs for 2019/2020 rock samples using company and lab duplicates, standards and blanks indicate good accuracy and precision in a large majority of standards assayed.
Analytical samples were taken from each 1-metre interval of channel floor resulting in approximately 2-3 kg of rock chips material per sample. Collected samples were sent to ALS Lab in Arequipa, Peru for preparation and then to Lima, Peru for analysis. All samples are assayed using 30 g nominal weight fire assay with atomic absorption finish (Au-AA25) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where MS61 results were greater or near 10000 ppm Cu, 10000 ppm Pb or 100 ppm Ag the assay were repeated with ore grade four acid digest method (Cu, Pb, Ag-OG62). Where OG62 results were greater or near 1500 ppm Ag the assay were repeated with 30 g nominal weight fire assay with gravimetric finish (Ag-GRA21). QA/QC programs for 2021 channel samples using internal standard and blank samples; field and lab duplicates indicate good overall accuracy and precision.
Silver equivalent grades (AgEq) were calculated using a $1300/oz gold price and $18/oz silver price. AgEq = Ag (ppm) + Au (ppm) * (Ag $/troy oz/Au $/troy oz). No metallurgy recovers were used for the AgEq calculation.
Analytical samples were taken by sawing HQ or NQ diameter core into equal halves on site and sent one of the halves to ALS Lab in Arequipa, Peru for preparation and then to Lima, Peru for analysis. All samples are assayed using 30 g nominal weight fire assay with atomic absorption finish (Au-AA25) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where MS61 results were greater or near 10,000 ppm Cu, 10,000 ppm Pb or 100 ppm Ag the assay were repeated with ore grade four acid digest method (Cu, Pb, Ag-OG62). Where OG62 results were greater or near 1,500 ppm Ag the assay were repeated with 30 g.
QA/QC programs for 2021 core samples using company and lab duplicates, standards and blanks indicate good accuracy and precision in a large majority of standards assayed.
Silver equivalent grades (AgEq) were calculated using silver price of US$18/oz and gold price of US$1,300/oz. Metallurgical recoveries were not applied to the silver equivalent calculation.
Main Interval - AgEq (Ag, Au) intervals at 25 ppm (minimum 5 m, max consecutive dilution 6 m)
Sub-Interval - AgEq (Ag, Au) intervals at 75 ppm (minimum 1 m, max consecutive dilution 2 m)
True widths of mineralization are unknown based on current geometric understanding of the mineralized intervals.