The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Deep copper discovery hidden below impressive surface showing North of 60 Mining News – August 4, 2023
Dark grey chalcocite, a sulfide mineral made up of roughly 79.8% copper, encountered in drillhole ST23-02 at Storm.
American West's deep drilling is testing gravity anomalies below the high-grade surface copper zones at Storm.
The gravity targets at Storm extend more than 10 kilometers (six miles) to the east into the Blizzard and Tornado prospect areas.
American West Metals Ltd. Aug. 2 announced that the first two holes of its deep diamond drill program at Storm have cut thick zones of copper sulfide mineralization associated with an enormous gravity geophysical anomaly, providing strong evidence that the impressive copper zones being outlined at surface are the tip of the proverbial copper iceberg on this property in the northern reaches of Canada's Nunavut territory.
"We are very excited to announce that the diamond drilling has had immediate success and produced spectacular results confirming the presence of a major copper system within the Storm Project," said American West Metals Managing Director Dave O'Neill. "The first two drill holes have discovered a new copper deposit below the near-surface mineralisation with both holes intersecting thick intervals of copper sulphide at the same stratigraphic horizon."
Storm has long been known for its pods of very high-grade copper at surface, and much of American West's drilling over the past two seasons has focused on building a resource around these shallow deposits that would support a mining operation envisioned to utilize ore sorting technology to upgrade the already high-grade mineralization to a direct shipping ore without the need for further processing.
At the same time, however, the company has been building evidence for a much larger high-grade copper orebody that underlies the copper deposits being outlined on the surface.
This evidence includes a recently completed gravity geophysical survey that has defined a series of dense features that are spatially associated with what is interpreted to be geological features similar to those found at large sediment-hosted copper deposits in Africa, as well as known copper sulfide mineralization at Storm.
Now, a first look at the core from drilling this deep target has further confirmed that the enormous gravity anomaly represents a very large body of impressive copper mineralization.
The first of the deep Storm Copper targets tested is a 2,300-meter-long dense body beginning at a depth of about 200 meters that is interpreted to represent a larger accumulation of copper sulfides under 4100N Zone, which has been the primary target of shallow reverse circulation drilling carried out this year.
This dense body identified by the gravity survey is intersected by a strong induced polarization (IP) geophysical anomaly on its upper contact.
ST23-01, the first 2023 deep hole to test this target, cut through 30.5 meters of 4100N Zone copper mineralization starting at a depth of 45 meters on its way to a 15-meter intercept of breccia and vein-style copper sulfide mineralization dominated by chalcopyrite from a depth of 332 meters.
The second deep hole, ST23-02, cut an even more impressive deep discovery intercept of 37 meters of breccia-style copper sulfide mineralization dominated by chalcocite from a depth of 333 meters. This is the first intersection of chalcocite, which consists of around 79.8% copper, at this depth.
Chalcocite is an important and high-value copper mineral that is often found in sediment-hosted copper deposits, including the deposits along the renowned Kalahari and Central African copper belts.
"This discovery is analogous to the world-famous copper belts in Africa that contain some of the world's largest and highest-grade copper deposits," said Thomas Ulrich, CEO of Aston Bay Holdings Ltd., which has optioned the Storm project to American West.
What makes these intercepts more exciting is they cut the same high-grade copper horizon 680 meters apart, indicating that the deep gravity anomaly does represent a very large body of high-grade copper mineralization at depth.
"The drill holes were targeting the first of a series of extensive gravity anomalies that were defined earlier this year, and have intersected a thick, sulphide and organic-rich unit," said O'Neill. "We believe this to be the source of the gravity anomalism, and given the large spacing between drill holes and size of the modelled gravity anomalies, the potential volume of mineralisation is very significant."
Gravity targets similar to the one tested by these first two holes extend more than 10 kilometers (six miles) to the east into the Blizzard and Tornado prospect areas on the Storm property.
"This is a major copper discovery," O'Neill added.
American West is drilling a third deep exploration hole to test a large gravity and electromagnetic anomaly about 1,700 meters south of hole ST23-02 and 1,000 meters west of 2750N, a zone of shallow high-grade copper mineralization.
Initial assays from the diamond drilling are expected in the next four weeks.
Even before the results are back from the assay labs, the deep Storm discovery is threatening to overshadow the shallow RC drill program at Storm, which is impressive in its own right.
The 2023 RC drilling began at 4100N Zone. Highlights from this drilling include:
• 29 meters averaging 1.1% copper from a depth of 59.4 meters in hole SR23-02, including a 1.5-meter subsection averaging 5.1% copper.
• 67.1 meters averaging 1.1% copper from a depth of 54.9 meters in hole SR23-03, including a 1.5-meter subsection averaging 7.1% copper.
• 10.7 meters averaging 1.3% copper from a depth of 76.2 meters in hole SR23-07, including a 1.5-meter subsection averaging 6.5% copper.
• 29 meters averaging 1.2% copper from a depth of 62.5 meters in hole SR23-13, including a 1.5-meter subsection averaging 8.2% copper.
• 25.9 meters averaging 1.3% copper from a depth of 61 meters in hole SR23-14, including a three-meter subsection averaging 3.7% copper.
• 15.3 meters averaging 1.6% copper from a depth of 59.4 meters in hole SR23-17, including a 3.1-meter subsection averaging 4.8% copper.
"The 4100N Zone has grown into a significant copper story," O'Neill said in early July. "The results from the latest batch of assays, along with geophysical interpretation, shows that the copper mineralisation is now over 1.3km (1,300 meters) long, 300m wide and open laterally in every direction. Additional extension and resource drilling will be completed to expand the footprint further."
In addition to continued expansion of 4100N, the RC drills are following up on similar near-surface high-grade copper mineralization at the 2750N and 2200N zones.
ST97-03, a hole drilled at the 2200N zone in 1997, cut 6.4 meters averaging 7.38% copper from surface and 22.35 meters averaging 1.56% copper from 22.9 meters.
Some of the most impressive near-surface copper mineralization historically drilled at Storm were encountered in 2750N, including: 110 meters averaging 2.45% copper from surface in hole ST97-08; and 56.3 meters averaging 3.07% copper from a depth of 12.2 meters in hole ST99-19.
American West's 2022 drilling at 2750N also cut strong mineralization over impressive widths, including: 57 meters averaging 2.5% copper from a depth of eight meters in hole ST22-02; and 41 meters averaging 4.18% from a depth of 83 meters in hole ST22-05.
"The RC drilling on the high-grade near surface deposits is also advancing rapidly, and we plan to give an update on the 2750N and 2200N Zone results shortly," said O'Neill.
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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