The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Hard evidence of past production, new prospects across Alaska
Tungsten carbide is used to make core drilling bits used by the mining industry, such as the Atlas Copco bit on the left. Diamond impregnated bits, such as the two on the right, however, are the most common choice for hard rock drilling.
TIG (tungsten inert gas) welding is among the many applications that take advantage of tungsten's extremely high melting point.
Incandescent light bulb filaments are another use that takes advantage of tungsten's ability to hold up to heat.
In addition to copper and gold, Freegold Ventures' Shorty Creek property in Interior Alaska also hosts intriguing quantities of tungsten and cobalt.
Extremely hard and with the highest melting point of all the elements on the periodic table, tungsten is vital to a broad spectrum of commercial and military applications, yet there are no mines in the United States producing this durable metal.
Nearly 60 percent of the tungsten consumed in the U.S. during 2018 was used to make the cemented tungsten-carbide, a compound of roughly equal parts tungsten and carbon.
Roughly twice as strong as steel, tungsten carbide is often found on the working end of drill bits, saw blades, wear plates and other items that require this compounds toughness to meet some of the most demanding conditions in the mining, oil and gas, construction and metal-working industries.
Tungsten carbide's hardness, coupled with a very high density, also makes this metallic compound ideal for making armor-piercing ammunitions for the military.
Because it retains its strength at high temperatures, elemental tungsten is used in many high-temperature applications. Heating elements, rocket engine nozzles and TIG (tungsten inert gas) welding are among the many applications that take advantage of tungsten's ability to hold up to heat.
A past producer of the tungsten minerals, wolframite and scheelite, Alaska could once again provide America a domestic source of these and other critical minerals.
China dominates tungsten
Like many of the 35 minerals and metals deemed critical to the United States, China controls the new tungsten coming into global markets.
"World tungsten supply was dominated by production in China and exports from China," USGS penned in its annual report, Mineral Commodity Summaries 2019.
At around 67 million metric tons of tungsten, the Middle Kingdom accounted for roughly 82 percent of the global titanium supply during 2018. The world's second largest tungsten supplier, Vietnam, produced 6 million metric tons last year. Russia, Austria and the United Kingdom round out the world's top tungsten sources.
In recent years, China has put limitations on tungsten mining and exports of this durable metal, causing concerns about global supply of this metal.
"China's government regulated its tungsten industry by limiting the number of mining and export licenses, imposing quotas on concentrate production, and placing constraints on mining and processing," the USGS wrote.
This effort has put constraints on the availability of tungsten concentrates in China.
While China touts stronger environmental safeguards as one of the primary reasons for restricting the mining of tungsten, as well as a host of other critical metals, many analysts believes the government's motives have more to do with consolidating mining to the country's largest producers and bolstering prices.
Whatever the impetus, China's production and export restrictions resulted in sharp increases in the price. During 2018, tungsten averaged US$330 per metric ton, a 35 percent increase over the US$245 per metric ton average the year before.
China also happens to be the largest consumer of tungsten, making it a major influencer on the demand side of the price equation.
"Beginning in 2017, economic conditions improved in China and elsewhere, resulting in increased tungsten consumption," USGS penned in its 2019 commodity summaries. "In early to mid-2018, prices of tungsten concentrate and downstream tungsten materials trended upward and then stabilized or decreased during the remainder of the year."
The United States consumed roughly US$900 million worth of tungsten during 2018, more than half of which came from foreign sources.
China, America's largest source of tungsten products, accounted for 32 percent of imports. Bolivia (9 percent), Germany (9 percent) and Canada (8 percent) were also contributors to U.S. needs for this durable metal.
Tungsten mining around Fairbanks
While there is not any tungsten produced in the United States today, this hard, industrial metal has been historically mined in several locations across Alaska.
The gold-rich hills around Fairbanks, in the heart of Alaska's Interior, is one of the past producing tungsten regions.
In 1915, Balkan immigrant Mike Stepovich discovered hardrock tungsten mineralization on the eastern flank of Gilmore Dome about 15 miles northeast of Fairbanks, which is near Kinross Gold Corp.'s currently producing Fort Knox gold mine.
Over the ensuing three years, Stepovich and his crew dug more than 2,000 feet of underground workings and produced 300 tons (600,000 pounds) of high-grade tungsten ore averaging 8 percent tungsten and 10 tons of concentrates that averaged about 65 percent tungsten trioxide.
With a substantial drop in tungsten prices at the end of World War I, however, Stepovich put a halt to his hardrock tungsten operations to resume mining the rich deposits of placer gold near Fairbanks, which is what drew him to Interior Alaska in the first place.
Stepovich's discovery, however, sparked interest in the regions tungsten potential.
"The scheelite deposits of the Fairbanks district are believed to be much more extensive than the surface outcrops show and to give promise of a large future production of tungsten," the USGS wrote in its 1917 report, "Mining in the Fairbanks District."
While this promise has yet to be fully realized, World War II rekindled interest in the tungsten around Fairbanks. In 1942, Cleary Hill Mines Co. leased the properties covering the tungsten lode from Stepovich and produced another 43,920 pounds, or nearly 22 tons, of tungsten trioxide.
All of Cleary Hill Mines' World War II production was sold to the U.S. Government-owned Metals Reserve Company.
Several other tungsten deposits and prospects were identified near Stepovich's discovery, including the Colbert lode, and Yellow Pup and Schubert prospects.
In the late 1970s and early 1980s, several tons of high-grade tungsten concentrates were shipped from Yellow Pup and un-milled ore was stockpiled there.
Exploring Circle, Fortymile districts
While the Fairbanks Mining District is a past producer of tungsten, it is not the only Interior Alaska mining district to host this critical metal.
"The Circle Mining District, including the Birch Creek area, has been known for years for its tin (cassiterite) and tungsten (wolframite and scheelite) minerals occurring in gold placer concentrates," James Barker penned in a 1979 U.S. Bureau of Mines report, "A trace element study of the Circle Mining District."
Barker's investigation found tungsten in most streams draining the Circle Hot Springs granitic intrusive, which is also the source of much of the gold in the heart of the Circle Mining District.
Sampling in the Lime Peak and Mount Prindle areas west of the intrusive also turned up tungsten and tin mineralization.
While the load source of tungsten in the Circle Mining District has not been identified, a sample of fresh granite collected by Barker at the upper end of Bedrock Creek, a stream known for its heavy tin mineralization, returned 22 parts per million tungsten, 20 ppm tin, as well as gold and molybdenum.
"Minable deposits of placer tin-tungsten minerals may exist in the Circle Mining District," Barker concluded.
The Fortymile Mining District, situated just across the border from Yukon's famed Klondike District, also has some interesting tungsten occurrences.
Doyon Ltd., an Alaska Native corporation representing 19,000 shareholders that have called Alaska's Interior home for millennia, owns tungsten prospective lands in the Fortymile.
These prospects, Duval Creek and Happy, were identified during investigations of the area in the 1970s.
Anomalous tungsten was discovered in stream-sediment and heavy-mineral concentrates in Duval Creek on what is now Doyon land during reconnaissance sampling in 1978.
Scheelite and molybdenite were discovered at Happy, located near Duval Creek, around the same time. Float boulders of quartz veins collected at Happy contained as much as 0.82 percent tungsten and 0.3 percent molybdenum.
These hints of tungsten add to the future potential of the Circle and Fortymile mining districts, regions of Interior Alaska that have produced some 2 million oz of placer gold.
Tungsten adds to Shorty Creek mix
Freegold Ventures Ltd. has found lode tungsten at its Shorty Creek property in the Livengood Mining District, about 70 miles north of Fairbanks.
Freegold discovered tungsten at Shorty Creek during it 2016 drill program to expand upon the porphyry copper-gold mineralization associated with a large magnetic high geophysical anomaly at the Hill 1835 target on the property.
SC 16-01 cut 207 meters averaging 0.045 percent tungsten trioxide; and SC 16-02 cut 409.6 meters averaging 0.03 percent tungsten trioxide.
Follow-up drilling last year continued to cut long sections of tungsten mineralization at Hill 1835, as well as the copper, gold, silver and cobalt also found at Shorty Creek.
Drilled about 200 meters southwest of the 2016 intercepts, hole SC 17-01 cut 360 meters averaging 0.24 percent copper 0.07 g/t gold, 4.04 g/t silver, 100 parts per million cobalt and 0.03 percent tungsten trioxide.
SC 17-02, drilled in the same area, cut 408 meters averaging 0.27 percent copper 0.05 g/t gold, 4.97 g/t silver, 85 ppm cobalt and 0.05 percent tungsten trioxide.
Hole SC 17-03, which was lost at a depth of 362.2 meters in strong mineralization due to mechanical difficulties, cut 105.2 meters averaging 0.27 percent copper, 0.05 g/t gold, 6.75 g/t silver, 114 ppm cobalt and 0.06 percent tungsten trioxide on the eastern edge of the magnetic high at Hill 1835.
One hole drilled at Steel Creek, another large magnetic anomaly about 1,500 meters northeast of Hill 1835, also encountered copper, gold, silver, cobalt and tungsten. While the mineralization was only anomalous, this first hole drilled into the target provides evidence of the larger prospectivity across the road accessible property.
The mix of base, precious and critical minerals at Shorty Creek has drawn the interest of Australian major South32 Ltd., which has agreed to invest up to US$10 million to this property over the next four years.
Friendliest tungsten ghost town
Interior is not the only region of Alaska to produce tungsten. During World War II this critical industrial metal was also extracted from the zinc-lead-copper concentrates produced from the Riverside Mine in the Hyder District of Southeast Alaska.
Located just across the border from Stewart, a British Columbia mining town at the southern tip of the Canadian province's famed Golden Triangle, the Hyder District experienced a boom of mining activity in the 1920s. While most mining in this region at the southern end of the Southeast Alaska panhandle faded in the 1930s, the Riverside Mine was revived in 1940.
Records show that 70,000 lb (35 tons) of tungsten, 3,000 oz of gold, 100,000 oz of silver, 100,000 lb of copper, 250,000 lb of lead and 20,000 lb of zinc was recovered from 30,000 tons of ore mined at Riverside.
At least six prospects – Last Shot, Mountain View, Fish Creek, Blue Bird, Monarch and Last Chance – have been identified across a 1.5- by three-mile area near the Riverside Mine, about 5.5 miles north of the town of Hyder.
While mining and mineral exploration is prolific around Stewart, there has been virtually no mining in the Hyder District just across the Alaska-B.C. border since the closing of the Riverside Mine.
The roughly 87 residents of Hyder embrace this disparity with the motto "the friendliest ghost town in Alaska."
Large, inaccessible Bear Mountain
The largest deposit of tungsten in Alaska, however, may lie in the Bear Mountain occurrence along the southern slopes of the Brooks Range.
During visits to Bear Mountain in the 1980s, Barker and fellow U.S. Bureau of Mines geologist R.C. Swainbank identified a 100-acre area of surface mineralization indicative of a large porphyritic molybdenum-tungsten deposit.
Analysis of 20 soil and 36 rock samples collected during 1985 returned abundant tungsten and molybdenum along with lessor amounts of niobium.
Soil samples collected over roughly 75-acres returned tungsten values of more than 500 parts per million wolframite, with the best samples containing 5,000 ppm of this tungsten mineral.
"I believe Bear Mountain to be likely the most important tungsten deposit in the U.S.," Barker told Mining News.
The potential of this intriguing tungsten-molybdenum discovery, however, may never be realized due to its location.
In addition to being located in a remote region of northeast Alaska, this potentially world-class tungsten-molybdenum deposit is situated within the Arctic National Wildlife Refuge, or ANWR, a 19.3-million-acre region set aside for wilderness and wildlife conservation.
"It's a shame that mineral evaluations aren't done before we place an area off limits," Barker reflected.
Rediscovering the Lost River Mine
While Bear Mountain may host the largest deposit of tungsten in Alaska, the Lost River skarn on the Seward Peninsula about 80 miles northwest of Nome likely holds the most promise for developing a tungsten mine in the state.
The significant amount of tin found in the aptly named Cassiterite Creek led early miners and prospectors to the Lost Creek deposit around 1902 and small-scale underground mining began there shortly after the discovery.
At the time, the tin found in this deposit was the target of mining. The tungsten, fluorite (or fluorspar) and beryllium also found there – all currently considered minerals critical to the United States – were largely ignored.
This mix of metals drew the interest of Lost River Mining Company, which planned to develop a mine there in the 1970s.
In preparation for developing a mine, roughly 16,100 meters of drilling in around 110 holes were drilled there at the time.
Based on this drilling, it was estimated that the Lost River skarn deposit hosts some 23.53 million short tons of resource averaging 16.43 percent fluorite, 0.26 percent tin, and 0.04 percent tungsten trioxide that could be mined by open pit methods; and 1.28 million tons of 11.66 percent fluorite, 0.15 percent tin, and 0.01 percent tungsten trioxide considered more suitable for underground mining.
According to this historical estimate, the surface minable portion of the Lost River deposit hosts 18.84 million lb of tungsten, 7.7 billion lb of fluorite and 122 million lb of tin.
Beryllium is also reported to be associated with this deposit but is not reported as a resource due to the difficulties recovering it.
Geologists familiar with Lost River, however, caution that further work needs to be done to shore up the historical estimate due to the spatial and mineralogic complexities of the deposit.
Considering the tungsten, fluorite, tin and beryllium found there – all considered critical to America's economic and strategic security – finding out just how much of these metals the Lost River deposit contains may well be worth the effort.
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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