The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Mining Explorers 2024 - January 15, 2025
Geologists Rachel Borg and Jordan Mathieu inspect core from 2024 drilling at Storm Copper.
Chalcocite and native copper blebs encountered while drilling a fault-offset extension of the Cyclone deposit.
A ship delivers supplies to Storm and picks up samples from the high-grade copper project alongside the Northwest Passage.
Since optioning Storm Copper from Aston Bay Holdings Ltd. in 2021, American West Ltd. has been discovering, defining, and expanding upon high-grade copper deposits at this project near the coast of a Nunavut Island along Northwest Passage shipping lanes that could be developed into a low-cost, open-pit mining operation that directly ships ore to global markets.
Without the cost or complexity of permitting and building a mill and tailings management facilities, a mining operation that just needs to crush the high-grade copper mineralization and then upgrade it to a direct shipping ore (DSO) using simple sorting technology would be significantly less expensive and much quicker to develop than a traditional copper mine.
The company took a major step toward its envisioned DSO operation at Storm with an inaugural resource calculated in early 2024 that outlined 17.48 million metric tons of Australian Joint Ore Reserves Committee- (JORC) compliant indicated and inferred resources averaging 1.17% (452 million lb) copper and 3.38 grams per metric ton (1.9 million oz) silver in four near-surface deposits within a roughly 10-square-kilometer (3.9 square-mile) area of the much larger Storm property.
"The maiden JORC-compliant mineral resource estimate for the Storm project has exceeded our expectations and delivered the foundations to what we believe will be a globally significant copper district," said American West Managing Director Dave O'Neill.
To build upon this maiden resource, the company completed more than 23,000 meters of drilling in 2024 focused on expanding the high-grade resources at Storm, testing a deeper high-grade copper horizon identified below the deposits, and exploring the wider potential across a 60-mile- (100 kilometers) long belt of copper and zinc mineralization covered by the Storm property on Nunavut's Somerset Island.
O'Neill said the 2024 program at Storm "continued to deliver significant milestones for the project including confirmation of the DSO potential, resource growth and increased confidence, and new discoveries of high-grade mineralisation near-surface and at depth."
Chalcocite and native copper blebs encountered while drilling a fault-offset extension of the Cyclone deposit.
Much of the 2024 program at Storm focused on upgrading and expanding high-grade copper mineralization at Cyclone, the largest of the four deposits defined so far at Storm.
According to the maiden resource calculation, Cyclone hosts 4.88 million metric tons of the overall indicated resource averaging 1.26% (135.8 million lb) copper; plus 7.21 million metric tons of the inferred resource averaging 1.2% (191.4 million lb) copper and 4.03 g/t (934,700 oz) silver.
Last year's drilling cut high-grade copper both within and beyond the margins of Cyclone. While the infill drilling returned dozens of copper intervals that will likely upgrade much of the inferred resource to the higher confidence indicated category, American West was particularly excited about wide intercepts of high-grade copper encountered outside the bounds of Cyclone. Highlights from these expansion holes include:
• 27.4 meters averaging 1.1% copper and 17.8 g/t silver from a depth of 96 meters in hole SR24-031.
• 53.5 meters averaging 3.9% copper and 12.56 g/t silver from a depth of 86.9 meters in hole SR24-093.
The high-grade copper encountered in these step-out holes were drilled across a fault that marks the southern edge of the currently defined Cyclone deposit highlights the significant resource expansion potential in the underexplored Central Graben area southwest of Cyclone.
The balance of the Storm Copper resource is found in the Chinook, Cirrus, Corona, and Chinook deposits along a roughly 2.5-mile (four kilometers) stretch of the South Graben Fault.
Chinook, the second largest and highest grade of the four deposits, is emerging as a favorite for a future DSO mine starter pit at Storm.
According to the inaugural calculation, Chinook hosts 2.19 million metric tons of Storm's inferred resource averaging 1.47% (71.2 million lb) copper and 4 g/t (282,000 oz) silver.
American West's 2024 program included drilling focused on upgrading much of the inferred resource at Chinook to the higher confidence indicated category and expanding the deposit.
The exceptional copper encountered with this drilling further bolstered Chinook's starter pit status. Highlights from the 2024 drilling at Chinook include:
• 14.1 meters averaging 4.9% copper and 7 g/t silver from a depth of 11.9 meters in hole SM24-02.
• 42.7 meters averaging 3.1% copper and 4 g/t silver from surface in hole SR24-068.
• 35.1 meters averaging 2.7% copper and 5.8 g/t silver from a depth of 22.9 meters in hole SR24-080.
• 29 meters averaging 2.6% copper and 4.3 g/t silver from surface in hole SR24-081.
"The drilling was designed to upgrade the current inferred resources and has also expanded the near-surface footprint of copper mineralisation," said O'Neill. "We believe this will enhance the development opportunity of Chinook, highlighting the deposit as a potential starter mine at Storm."
The two other deposits included in the inaugural Storm resource, Cirrus and Corona – are found at opposite ends of the Southern Graben Fault that runs along the southern boundary of the current Storm Copper resource areas.
Electromagnetic geophysical surveys, surface sampling, and drilling have identified at least four highly prospective targets – Lightening Ridge, Thunder, Squall, and The Gap – along this fault between Cirrus and Corona. Highlights from holes testing these resource expansion targets include:
• 48.6 meters averaging 3% copper from a depth of 32.4 meters in hole ST23-03 (Thunder).
• 20 meters averaging 2.3% copper from a depth of 38 meters in hole SR24-03 (Gap).
In December, incorporated this drilling into a new mineral reosource estimate. According to the new calculation, Cyclone, Chinook, Corona, Cirrus, Thunder, and Lightening Ridge – host 20.61 million metric tons of combined indicated and inferred resources averaging 1.11% (504 million lb) copper and 3.34 g/t (2.2 million oz) silver.
Cyclone and Chinook now host 10.62 million metric tons of indicated resources averaging 1.3% (304 million lb) copper and 4.13 g/t (1.4 million oz) silver – a 117% increase over the previous estimate.
"This year's drilling has significantly derisked the Storm resource and moved a lot of the copper metal at the Cyclone and Chinook deposits into the indicated JORC category," said O'Neill. "This classification is essential for permitting and the ongoing assessment of the project and allows us to develop robust mine plans and economic models."
A ship delivers supplies to Storm and picks up samples from the high-grade copper project alongside the Northwest Passage.
In addition to starting out with deposits with average grades of well above 1% copper and thick zones of mineralization above 3% copper, the style of copper mineralization and host rock makes Storm particularly well-suited for a DSO mining plan being developed by American West.
The dominant copper mineral within the Storm deposits is chalcocite, a dark grey and heavy copper sulfide mineral that contains 79.8% copper. The coarse chalcocite veins and breccias are hosted within a light grey or brown dolomite (a type of limestone) with a specific gravity of around 2.85%, which is half of the roughly 5.7% specific gravity for chalcocite.
The large difference in physical properties indicates the potential to easily separate the heavy and dark-colored copper mineralization from the much lighter host rocks.
Ore sorting, which uses a variety of sensors and algorithms to identify material properties and then separate them in real time, has the potential to upgrade the Storm Copper mineralization to a DSO.
This processing technique is widely used by the mining industry to upgrade ore at global mines that produce gold, lithium, iron ore, nickel, and other minerals and metals.
Studies completed last year confirmed the potential of using an ore sorter equipped with X-ray transmission sensors and an inline jig to create a DSO product at Storm with grades topping 16% copper.
"The DSO test program has produced commercial grade DSO products from typical copper ores through an uncomplicated and low-cost process," said O'Neill. "This is game-changing for the Storm project and world-leading in terms of copper processing innovation and performance."
After mining and crushing, any Storm Copper ore over 0.4 inches (10 millimeters) would be sent to the ore sorter, where an XRT sensor would identify and reject any unmineralized rock. Ore smaller than 0.4 inches would be run through the jig, which would use gravity separation to produce direct shipping ore.
The study carried out by ALS Metallurgy, Sacre-Davey, and Nexus Bonum – found that a 1.5-million-metric-ton-per-year plant with ore sorting and jig circuits could produce between 10,000 to 16,000 metric tons of copper per year in a concentrate averaging 16 to 22% copper from the Cyclone and Chinook deposits.
The annual copper production from Chinook would be higher due to the higher grades of mineralization contained within that deposit.
"The process of generating DSO at Storm is amazingly simple and highlights our company's focus on generating ESG sensitive and low capital development solutions," the American West managing director said. "Storm Copper now stands out as one of the very few, and highest-grade DSO copper opportunities globally."
While advancing the DSO opportunity and the near-surface, high-grade copper properties that support it, American West is exploring the upside potential at Storm, including a deeper horizon of copper mineralization below the deposit outlined so far and testing early staged targets across the 219,257-hectare (541,796 acres) property.
The 2024 deep drilling program added to the evidence that a very large copper system lies below the near-surface deposits that are distributed across a 10-square-kilometer– (3.8 square miles) area at Storm – highlighting the potential for large-scale stratigraphic hosted copper deposits similar to those found along the famed Central African Copperbelt
American West first tested the deep copper potential with a 2022 hole targeting an electromagnetic anomaly below Cyclone. This hole, ST22-10, cut five layers of low-grade zinc from depths of 29 to 150 meters, three layers of low-grade copper from 313 to 325 meters, followed by another layer of low-grade zinc starting at 358 meters.
Five widely spaced deep holes drilled in 2023 cut sediment-hosted copper mineralization associated with an enormous gravity geophysical anomaly depth, including 37 meters of breccia-style copper sulfide mineralization dominated by chalcocite from a depth of 333 meters in hole ST23-02.
Three holes drilled in 2024 – each drilled about two kilometers (1.2 miles) apart – confirmed the lateral extent and high-grade nature of the "Deep Copper Horizon" at Storm.
As the drills turned within the main Storm and Storm Deep resource area, electromagnetic geophysical identified two EM anomalies associated with Tornado, a high-potential copper prospect about 10 kilometers (six miles) east of Storm. The geological setting is interpreted to be identical to that of Storm and contains numerous outcropping copper occurrences.
The company is also looking forward to further exploration at Tempest, a prospect about 25 miles (40 kilometers) south of the Storm Copper resource, where rock samples collected in 2023 returned grades of 38.2% copper and 30.8% zinc.
Overall, the district-scale Storm property covers a 100-kilometer (60 miles) trend of sediment-hosted copper targets and deposits reminiscent of the world-class copper belt running across Africa.
Reflecting on the success of the 2024 exploration campaign at Storm, O'Neill said, "These achievements have significant implications for the exploration potential of the project and highlight clear similarities of Storm to the large-scale copper deposits in the Congo and Botswana."
American West's envisioned DSO operation at Storm may mark the emergence of a North Canadian Copper Belt running across Nunavut's Somerset Island.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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