North of 60 Mining News - The mining newspaper for Alaska and Canada's North

Ambler Metals LLC's US$27 million work program slated for the Upper Kobuk Mineral Projects in Northwest Alaska includes 14,600 meters of drilling directed at a wide variety of targets, from condemnation drilling where the company plans to build the processing plant and tailings facility at the Arctic Mine project to exploring for new deposits of carbonate-hosted copper-cobalt mineralization in the Cosmos Hills.

Trilogy Metals Inc. and South32 Ltd., equal owners of the Ambler Metals joint venture, will advance the highest priority projects and exploration targets across the 426,600-acre UKMP.

The 2021 program has three overarching priorities:

• Arctic project – Drilling at Arctic will include additional infill drilling to further improve the confidence of the mineral resources, as well as additional metallurgical and condemnation drilling to allow the partners to further de-risk the proposed mine.

• Arctic Hub – Exploration drilling aimed at discovering copper-rich satellite deposits within a 5,000-meter radius of the Arctic deposit.

• District exploration – This will include drilling and other exploration for volcanogenic massive sulfide deposits similar to Arctic across the Ambler VMS Belt and carbonate-hosted deposits like Bornite in the Cosmos Hills and the Ambler Lowlands.

"The proposed exploration program will be one of the biggest programs in the history of the Ambler Mining District and we have expectations that this program will eventually add to our mineral inventory within this emerging world-class mining district," said Trilogy Metals President and CEO Tony Giardini.

Ambler Metals planned to carry out much of this work this year but decided not to carry out a 2020 field program due to the COVID-19 pandemic.

Looking ahead to the 2021 field season, Ambler says it will be adhering to strict COVID safety protocols that include requiring negative COVID-19 tests before traveling to site and prior to departing project, social distancing, face masks, and sanitization.

"We are looking forward to executing a safe and productive summer field season, expecting to hire approximately 60 personnel directly and an additional 75 through contractors working with us," said Ambler Metals President and CEO Ramzi Fawaz. "We will of course prioritize hiring NANA shareholders from the Upper Kobuk villages followed by other shareholders in the NANA region and will be applying strict COVID protocols to protect our employees, contractors and the communities around us."

Arctic drilling

A 2020 feasibility study details plans for a financially robust mine at the Arctic deposit that would produce 1.9 billion pounds of copper, 2.3 billion lb of zinc, 388 million lb of lead, 386,000 ounces of gold, and 40.6 million oz of silver over an initial 12-year mine life.

This operation is based on 43 million metric tons of reserves averaging 2.32% copper, 3.24% zinc, 0.57% lead, 0.49 grams per metric ton gold, and 36 g/t silver.

While high-grade VMS deposits such as this are typically mined from underground, the Arctic feasibility study proposes a lower-cost open-pit mine feeding a 10,000-metric-ton-per day mill.

The 2021 field program at Arctic will include 7,600 meters of drilling aimed at both extracting additional material for metallurgical work and upgrading mineral resources into the measured category, which could then potentially be upgraded to reserves.

This will include around 2,000 meters of geotechnical drilling in eight holes, 4,800 meters of resource conversion-metallurgical drilling in 28 holes, and 800 meters of condemnation drilling in four holes.

The condemnation drilling will provide geological information for the areas near the Arctic deposit where Ambler plans to build the processing plant and tailings management facility.

The goal of this summer campaign at Arctic is to advance and de-risk the project so the joint venture partners can make a future construction decision.

Arctic Hub

Ambler Metals has also identified three high-priority VMS target areas within 5,000 meters of the Arctic deposit that will be tested with 2,250 meters of drilling this summer:

• East Arctic – This target only about 200 meters east of the Arctic deposit is believed to host an extension of the three lowermost mineralized zones in the resource. Gossan – oxidized and weathered outcrop – on the eastern slope supports the idea of this potential Arctic extension.

• Southeast Arctic – This target, about 1,700 meters southeast of Arctic, includes an electromagnetic conductor that coincides with alteration hyperspectral response located with hyperspectral imaging on the projection of the Arctic mineralized horizon.

• Center of the Universe – A large target area covering the catchment immediately northwest of Arctic Valley that hosts multiple fold-fault repeats of the Arctic stratigraphy that coincide with electromagnetic geophysical and soil geochemical anomalies.

In addition to drilling, crews will carry out geological mapping and soil sampling over several prospects and geophysical anomalies outside these target areas, including the Pipe VMS prospect about 4,000 meters northeast of Arctic.

Detailed geological and structural mapping at Arctic and in the surrounding area will be used to build a three-dimensional geological model of the favorable geological horizons for VMS mineralization. This model is expected to be used for future exploration.

More VMS targets

Ambler Metals will also test three targets across the wider Ambler VMS Belt – Sunshine, Snow, and Cliff-DH-Horse – with 2,900 meters of drilling this year.

According to a calculation completed for Kennecott Mines in 1997, Sunshine hosts 20 million metric tons of historical resource averaging 1.4% copper, 2.5% zinc, 0.5% lead and 28.1 g/t silver.

Located about eight miles (13 kilometers) northwest of Arctic, Sunshine was the target of 2019 drilling by Trilogy that confirmed the robust nature of the Arctic-like VMS mineralization found there.

The planned drilling will test the west-southwest extension of high-grade intercepts in SC19-019, a hole completed by Trilogy Metals that cut 8.1 meters averaging 3.28% copper, 1.47% zinc, 0.27% lead, 0.15 g/t gold, and 25.64 g/t silver; and 7.88 meters averaging 2.23% copper, 5.62% zinc, 1.1% lead, 0.18 g/t gold, and 46.95 g/t silver.

Located on a ridge north of the Ambler River about 19 miles (30 kilometers) northwest of Arctic, Snow is a silver- and zinc-rich prospect discovered in the 1970s. This year's drill will test the down-dip extension of silver- and zinc-rich mineralization encountered by previous drilling.

Located about 12 miles (19 kilometers) northwest of Arctic, Cliff-DH-Horse hosts VMS mineralization intersected in 12 of 18 holes drilled over a strike length of 3,000 meters during the 1970s.

Ambler plans to test potential mineralization with further drilling this year.

In addition, the company plans to carry out mapping and soil sampling at several other VMS prospects in the belt, including Ambler, Dead Creek, South Cliff, Nora, and roughly 10 high-priority electromagnetic anomalies identified during a 2019 versatile time domain electromagnetic (VTEM) survey carried out by Trilogy in 2019.

Exploring Bornite lookalikes

In addition to seeking new sources of VMS mineralization, Ambler Metals' 2021 program will target carbonate-hosted copper-cobalt mineralization similar to Bornite, the second most advanced UKMP project.

Located about 16 miles (26 kilometers) southwest of Arctic, Bornite hosts 6.4 billion lb of copper and 77 million lb of cobalt in near-surface and underground deposits.

At a cut-off grade of 0.5%, the open-pit portion of Bornite hosts 40.5 million metric tons of inferred resource averaging 1.02% (913 million pounds) copper; and 84.1 million metric tons of indicated resource averaging 0.95% (1.77 billion lb) copper.

At the same cut-off grade, the Bornite open-pit also hosts 124.6 million metric tons of inferred resource averaging 0.017% (45 million lb) cobalt.

The below-pit portion of Bornite, at a cut-off grade of 1.5%, hosts 57.8 million metric tons of inferred resource averaging 2.89% (3.68 billion lb) copper and 0.025% (32 million lb) cobalt.

"While we will not be drilling at the Bornite project this year, we believe in the potential of this project and plan to resume drilling there soon," said Giardini.

This year's program, however, will include exploration for other carbonate-hosted copper-cobalt mineralization in the Cosmos Hills that host Bornite and along strike in the Ambler Lowlands.

Outside of exploration work on the Bornite deposit itself, the Cosmos Hills have not been systematically explored since historical work was carried out by Kennecott in the 1990s.

Trilogy Metals Inc.

Mapping and soil sampling planned for this year will cover a roughly six-mile- (10 kilometers) long area from the Aurora and Pardner Hill copper prospects in the west to Bornite East and will be used to define drill targets for 2022.

The Ambler Lowlands is a six-mile- (10 kilometers) wide glaciated valley between Arctic and Bornite that is virtually unexplored. NANA-1, one of only two holes ever drilled in this valley, was completed in 1974 and believed to have intersected dolomitized carbonate and carbonate breccia similar to the carbonates that host the Bornite deposit approximately nine miles (14 kilometers) to the west. Ambler says this drill hole indicates the potential for Bornite-style carbonate-hosted copper-cobalt mineralization concealed under shallow glacial cover in the lowlands and will be followed up with drilling this year.

Author Bio

Shane Lasley, Publisher

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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