By Shane Lasley
Mining News
Large Storm Copper drill program brewing
North of 60 Mining News – March 1, 2024
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Last updated 5/8/2024 at 3:09pm
RC drilling at the Cyclone deposit during American West's 2023 program at Storm Copper.
American West plans to expand high-grade resources, test discovery targets this year.
American West Metals Ltd. Feb. 26 announced plans for 22,000 meters of resource expansion, definition, and exploration drilling this year at its high-grade Storm Copper project on Nunavut's Somerset Island.
In mid-February, American West reported the first-ever industry-compliant resource estimate for Storm. According to this calculation, four deposits within a roughly 10-square-kilometer (3.9 square miles) area of the Storm property host 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.
"The maiden JORC-compliant mineral resource estimate (MRE) 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 Metals Managing Director Dave O'Neill.
To continue to unveil this potential, this year's reverse circulation and diamond drill program will focus on expanding the resource, defining resources at other targets within the Storm resource area, test new high-grade copper zones along strike and below known copper exploration, and explore other targets along a more than 100-kilometer (60 miles) copper belt that spans the wider Storm property.
"The drilling this year will aim to immediately build the copper inventory around the known deposits and high-grade prospects, and to explore the emerging, large-scale sedimentary copper system," said American West Metals Managing Director Dave O'Neill.
Resource expansion targets
This year, American West has identified four primary targets – Thunder, Lightning Ridge, Cyclone North, and The Gap – for resource expansion drilling.
The company says high-grade copper mineralization within broad electromagnetic (EM) geophysical anomalies has been identified at all these prospects.
While EM anomalies have a 100% correlation to high-grade copper at Storm, induced polarization (IP) geophysics has also proven effective in identifying network textured and vein-hosted sulfides. With this in mind, the company recently reviewed and reinterpreted historical IP data using a "metal factor" algorithm to filter the data and define areas likely containing metallic sulfides.
The new imagery from this reinterpretation highlights a series of extensive IP anomalies that coincide with the known copper deposits and main structures of the graben fault system that delivered the copper-bearing fluids to the deposits.
A map of the deposits that host the current Storm Copper resources (magenta) and targets identified with a reinterpretation of historical IP geophysical data.
Of particular interest is a newly defined anomaly that is located immediately south of the Cyclone deposit, which hosts roughly 70% of the overall Storm resource. This deeper anomaly, which has never been drilled, is roughly the same size as the currently outlined Cyclone deposit.
This is in addition to a large expansion target area immediately north of Cyclone.
The other resource definition targets within the immediate Storm resource area are Lightning Ridge, where 2023 drilling cut 15.2 meters averaging 2.3% copper; Thunder, where 2023 drilling cut 48.6 meters averaging 3% copper; and The Gap, where 2018 drilling cut 1.5 averaging 4.4% copper.
"The initial Storm copper resource is blessed with outstanding and immediate growth potential," said O'Neill. "The known copper deposits remain open, and the high-grade Thunder, Lightning Ridge and Cyclone North discoveries of 2023 are not yet included in the MRE (mineral resource estimate)."
Overall, American West plans to carry out 12,000 meters of resource expansion and definition drilling this year.
Districtwide exploration
The remaining 10,000 meters of drilling will focus on exploring the larger potential at Storm. This will include further investigations of deeper sediment-hosted copper mineralization below the current resource area, as well as other targets across the district-scale property.
In 2022 and 2023, American West began testing the deep copper potential at Storm. All five holes 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. Chalcocite, a mineral that runs about 79.8% copper and is often found in the sediment-hosted copper deposits along the renowned Kalahari and Central African copper belts, is a great indicator of the deeper copper potential.
"All five deeper diamond holes have intersected the sediment-hosted copper system with the wide-spaced nature of the holes indicating the very large lateral extent of the system," O'Neill said.
This year's exploration drilling will also test Blizzard and Tornado, prospects that lie five to 10 kilometers (three to six miles) east of Storm.
Blizzard is defined by a 4,000-meter-long by 1,500-meter-wide oval-shaped EM target coincident with elevated levels of copper in rock and soil samples.
Tornado is centered on an area with abundant copper-mineralized (chalcocite and malachite) boulders within a 3,200-meter by 1,500-meter geochemical copper anomaly.
Both the Tornado and Blizzard prospects also host several strong gravity anomalies similar to those defined at Storm during 2023. The gravity anomalies are located in highly favorable geological locations and are coincident with the soil and rock copper anomalies.
The 2024 program will also include further exploration of Tempest, a prospect roughly 40 kilometers (25 miles) south of the known copper discoveries at Storm, where historical sampling of gossans (oxide minerals often capping orebodies) returned grades as high as 32% copper.
Seven samples collected from Tempest by American West geologists in 2023 returned grades up to 38.2% copper and 30.8% zinc.
An EM and magnetic survey completed over Tempest last August has defined a series of conductive anomalies that lie along the strike of the stratigraphy and are coincident with the copper-zinc gossans in a number of areas.
"There are numerous underexplored targets within the highly prospective, 100km strike length of the copper horizon. The expansion of the exploration into these areas along this trend will aim to demonstrate the belt scale opportunity that exists at the project," said O'Neill. "The Tempest, Blizzard and Tornado areas are particularly exciting as they host large volumes of outcropping copper and high-priority geophysical targets."
The 2024 exploration program at Storm is slated to get underway in March.
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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