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

After establishing its position as a leading zinc-lead-silver explorer in northern Canada, Fireweed Metals Corp. set out in late 2022 to broaden its focus in both geography and commodities.

Partly defying the age-old adage to stick to what you know, the longtime explorer of the district-scale Macmillan Pass zinc-lead-silver project ventured across the border into Northwest Territories to acquire two projects.

While the Gayna River zinc-lead-silver-gallium-germanium project is within Fireweed's demonstrated wheelhouse, the giant Mactung tungsten project it purchased in early 2023 is charting into new waters both in terms of commodity and the near-development stage of the project.

Located within the traditional territories of the Kaska Dena and Na-Cho Nyäk Dun First Nations and the Sahtú Settlement Area, the Mactung deposit covers 37.6 square kilometers (14.5 square miles) and straddles the Yukon-NWT border about 13 kilometers (eight miles) north of Fireweed's Macmillan Pass Project and 230 kilometers (143 miles) from the nearest town, Ross River in Yukon Territory.

Exploration since the 1960s

Mactung was discovered and staked in 1962 by an Amax company geologist. Extensive drilling, metallurgical testing, and multiple historical resource estimates were completed during the next 20 years. The property changed ownership several times and was eventually acquired by North American Tungsten Corp. in 1997.

In 2009, that company published a positive feasibility study for its Mactung project and Yukon regulators approved a development plan for a mine in 2014.

However, North American Tungsten ran into operating difficulties with its Cantung tungsten mine located to the southeast and filed for protection from its creditors. Northwest Territories government purchased the Mactung project for $4.5 million in 2015 and subsequently obtained a Class 4 Mining Land Use Approval in 2020 for mineral exploration activities in the Yukon.

In 2022, Fireweed signed an agreement with the NWT government to purchase the Mactung project.

A few months later, Fireweed reported a mineral resource estimate for the massive deposit after verifying earlier work at Mactung.

"In one year, we have gone from signing an initial Letter of Intent to a Definitive Asset Purchase Agreement to the publication of a new mineral resource for Mactung," Fireweed CEO Brandon Macdonald said this summer. "We have taken the historic resource through a process involving relogging, resampling, and a rigorous, modern estimation methodology, and confirmed an impressive and world-class tungsten resource at Mactung."

The updated estimate reported that Mactung hosts 41.5 million metric tons of indicated underground and open pit resource averaging 0.73% (665 million pounds) tungsten trioxide and 12.3 million metric tons of inferred underground and open pit resource averaging 0.59% (158.7 million lb) tungsten trioxide.

"This not only reaffirms Mactung's unmatched combination of grade and scale but establishes it as a truly strategic critical minerals project for the West with the underground resource alone able to supply much of North America's expected demand for decades," said Macdonald.

The explorer also reported estimates for copper and gold as significant by-product metals at Mactung.

Based on historical production of small quantities of gold and copper concentrate from the geologically similar Cantung mine, the explorer is assuming in the current mineral resource that gravity separation and a copper circuit can be incorporated into a mine flowsheet to recover a portion of the gold and copper to satisfy reasonable prospects of eventual economic extraction.

Fireweed estimated 15.7 million pounds of copper grading 0.058%, plus 30,000 ounces gold grading 0.078 grams per metric ton in indicated underground mineral resources, along with 1.2 million lbs copper grading 0.02%, plus 2,000 oz gold grading 0.017 g/t in inferred underground resources at Mactung.

Mactung's current mineral resource estimate ranks it as the world's largest high-grade tungsten resource in the world.

A new exploration target

Fireweed also has reported potential for a new exploration target at Mactung of 2.5 million to 3.5 million metric tons, grading 0.4% to 0.6% tungsten trioxide in addition to its current mineral resources.

The exploration target is within the current geological model and is supported by drilling and surface mapping. The target also includes material located beyond the boundaries of the project's inferred and indicated resources but within the boundaries of the open-pit shell and underground volumes used to constrain the current mineral resource.

The target, however, is conceptual in nature and will require additional drilling to test the geological model, grade continuity, and extent of mineralization, the company said.

Fireweed and its consultants also conducted metallurgical tests recently to validate the recovery of tungsten and assess the recovery of gold and copper at Mactung. Grades of copper and gold for open-pit constrained resources were considered too low to include in the recent mineral resource statement, the company added.

The underground mineral resource at Mactung is within a gently to moderately dipping, roughly tabular, lower zone that is about 20-30 meters thick, extending for a kilometer in strike and up to 380 meters down-dip.

In the upper zone, a high-grade open pit resource was constrained by a conceptual pit shell at a 0.25% tungsten trioxide cut-off grade.

Additional bulk density and assay data were collected during an extensive Fireweed campaign of re-sampling of historic drill core in late 2022 and early 2023, resulting in Fireweed's new geological interpretation of the deposit.

A most critical mineral

Tungsten is the hardest metal with the highest melting point, which makes it an important and often essential metal for use in the automotive, technology, energy, military, and manufacturing industries.

The global tungsten market is projected to exceed US$9.3 billion by 2031, with demand averaging annual growth of 7.8% during the next eight years.

China is the global leader in tungsten production, and currently the West can boast of only limited output. As a result, the element is deemed a critical mineral by many governments, including Canada and the United States.

To support and advance the exploration and mining of critical minerals in Canada, including zinc and tungsten, the Canadian government has developed several initiatives.

Focus on mine development

MacDonald said Fireweed will collaborate with federal, territorial, and Indigenous governments to advance Mactung through the permitting and detailed engineering stages of the project.

Toward that end, the junior recently appointed mine-building expert Patrick (Paddy) Downey.

Fireweed Metals Corp.

With 40-plus years of international experience in mine operations, development and construction, Downey is currently CEO of Orezone Gold, where he has overseen the successful financing, construction, and operation of the Bomboré mine in Burkina Faso.

He has held the position of president, CEO and director of Elgin Mining Inc., Aura Minerals Inc., and Viceroy Exploration Ltd. before its acquisition by Yamana Gold Inc. in 2006, as well as numerous senior engineering positions at several large-scale global gold mining operations and has also held operating positions at several mining projects in northern Canada.

Downey has also served on the boards of numerous mining companies, including Victoria Gold Corp., during the development stage of Yukon's Eagle Gold Mine.

Fireweed also recently raised C$16.8 million in private financing.