The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Aussie explorer expands high-grade skarn, seeks bigger prize
Copper stained outcrop at the Mars prospect, an area of the Alaska Range property where geochemical and geophysical evidence suggest the presence of a buried porphyry deposit.
Hole ZX-18018 cut three zones of copper-gold mineralization about 100 meters below the 2018 resource for the Zackly skarn deposit on PolarX' Alaska Range property.
PolarX Ltd. has put together an 85,750-acre (347 square miles) land package just off Alaska's road system that already hosts deposits rich in copper and gold yet remains vastly under-explored.
This 22-mile- (35 kilometers) long property, known as Alaska Range, is made up of two adjacent projects – Stellar and Caribou Dome – the Australia-based exploration company brought together in 2017.
Stellar, currently the primary focus of PolarX's exploration, already boasts 90.4 million pounds of copper, 213,000 ounces of gold and 1.5 million oz of silver in a high-grade skarn deposit known as Zackly.
Caribou Dome, situated immediately southeast of Stellar, hosts its own high-grade copper deposit with roughly 190 million pounds of copper.
PolarX's first order of business is to build enough copper-gold inventory between Zackly and Caribou Dome to support a feasibility study for an economically viable mining operation, or two, at Alaska Range.
The company, however, believes these high-grade deposits found at the surface may very well represent the tip of the iceberg in terms of the much larger potential of this stretch of the Alaska Range.
The vast and underexplored potential in a low-risk jurisdiction is what attracted PolarX to Alaska and why so many other Aussie mineral explorers and mining companies are looking North to the Last Frontier.
"Great mineral wealth, low sovereign risk, opportunity to make world-class discoveries and culturally similar," PolarX Ltd. Executive Director Jason Berton listed as reasons when Mining News asked about a recent surge in Australian companies investing in Alaska.
Australia-Alaska partnership
Berton first began exploring Alaska's great mineral wealth with Vista Minerals Pty Ltd., a privately held Australian exploration company that he founded.
"At the time the exploration market was in a deep recession globally, and I thought it was a good time to enter Alaska," he said. "My initial thoughts were to capitalize on the market downturn in a jurisdiction that is well-endowed with mineralization, relatively unexplored and safe from a sovereign risk perspective. If you take that approach, Alaska ends up high on your list."
High on Berton's list of Alaska projects was Stellar, a high-grade copper-gold project held by Millrock Resources Inc., an Alaska-based project generator with a portfolio of gold and copper exploration properties across the state.
While Vista and Millrock were investigating Stellar, another Australian exploration company, Coventry Resources, was expanding high-grade copper at the adjacent Caribou Dome project.
Early in 2017, the two Australia-based companies merged to form PolarX. As part of the merger, Millrock offered up its interest in Stellar for what is now a roughly 9.76 percent interest in the resulting company, PolarX.
With Stellar and Caribou Dome under one Australian roof, PolarX focused its 2017 program on upgrading a historical resource for the Zackly deposit to Australian Joint Ore Reserves Committee mineral reporting standards.
Carrying forward a relationship built with Visa Minerals, Millrock is lending it local acumen to Alaska Range as manager of the exploration programs there.
Berton said this Alaska-Australia partnership has been a key to PolarX's quick success in Alaska.
"I started Vista as a one-man band a long way from home, so I needed to establish support in Alaska as quickly as possible," the Australian geologist said. "Millrock has been able to establish the exploration work force and contractors we use to implement our last three field seasons.
"It's an enormous undertaking each time to prepare for the field season. Without Millrock performing that task I'd have to establish all the team and networks in-country myself, which I've done previously in Chile, so I appreciate how difficult that can be," he added.
Another advantage Millrock brings to the project is a deep understanding of the Far North state and the rocks found there.
"I've found that if a geologist lives in Alaska they're committed to two things – geology and Alaska. The combination makes for a great work ethic and deep understanding of the local environment, which is something that as a foreigner I need to be successful here," Berton said.
Expanding Zackly
Merging Stellar and Caribou Dome into a single property that blankets a 22-mile stretch along the south slopes of the Alaska Range rich in copper and gold, PolarX set out to achieve its goal of building enough resources to consider the economics of developing a mine.
Zackly, a gold- and copper-rich skarn deposit at Stellar with a significant historical resource and exceptional expansion potential, was the logical place to start.
A 13-hole drill program carried out in 2017 provided enough information to upgrade Zackly to 3.4 million metric tons of inferred resource grading 1.2 percent (90.4 million pounds) copper, 2 grams per metric ton (213,000 oz) gold and 14 g/t (1.5 million oz) silver, that meets Australian Joint Ore Reserves Committee (JORC) mineral reporting standards.
This shallow deposit, now referred to as Main Skarn, has been traced for a length of about 1,000 meters and PolarX said it is clearly open along strike and at depth. The Australian explorer targeted these resource expansion areas this year.
"The fact that we have readily upgraded the resource to JORC standard, while maintaining the same quantity of contained metal further underpins our confidence in the potential to significantly expand the project," PolarX Managing Director Frazer Tabeart said.
The copper and gold mineralization being cut well beyond the resource is bolstering this confidence.
ZX‐18020, drilled about 850 meters east of the resource boundary cut 54.6 meters averaging 2.8 g/t gold, 9.4 g/t silver and 0.6 percent copper, including a 0.3-meter (one foot) section from 56.7 meters averaging 27.3 percent copper, 2.5 g/t gold and 82.5 g/t silver.
Berton said the gold and copper cut in hole 20 takes PolarX "a step closer to achieving the minimum resource threshold to justify an economic appraisal of Zackly."
ZX-18018, which cut three zones of copper‐gold mineralization 100 meters below the nearest hole in the current JORC-compliant resource, moves Zackly another step closer.
From a depth of 261.6 meters, this hole cut 25.5 meters averaging 0.6 percent copper, 1.5 grams per metric ton gold; and 5.5 g/t silver; 13.9 meters of 0.6 percent copper, 1.1 g/t gold and 4.7 g/t silver from 300.8 meters; and 4.7 meters of 1.3 percent copper, 2.1 g/t gold and 10.6 g/t silver from 326.1 meters.
Higher grade sections of these longer intercepts include 1.4 meters of 3.2 percent copper, 9.3 g/t gold and 38.2 g/t silver from 285.8 meters; and 2.5 meters of 2.3 percent copper, 3.5 g/t gold and 18.5 g/t silver from 326.1 meters.
Hole ZX-18023, drilled 350 meters east of the currently defined Zackly deposit and 500 meters west of ZX-18020, cut 9.3 meters of magnetite skarn containing 3.3 percent copper, 2.3 g/t gold and 19.7 g/t silver.
ZX‐18025 cut 11.4 meters of skarn mineralization with visible copper sulfides about 40 meters below ZX-18023.
Tip of the iceberg
PolarX believes the skarn deposit at Zackly may represent a high-grade tip of a much larger mineral iceberg on the Stellar property.
Geophysics carried out across the Stellar property show that the Zackly skarn lies just east of the mid-point of a 6,000-meter long corridor that is prospective for deeper porphyry mineralization, deposits that tend to be much larger but lower grade than the skarns associated with them.
The 2017 drilling at Zackly encountered porphyry‐style veins and related copper sulfides, and drilling this year is providing further evidence that a much larger deposit might lie in wait.
Zackly SE, a prominent magnetic anomaly about 2,000 meters southeast of the current resource is one area PolarX believes could host one of these much larger porphyry deposits.
The thick zone of gold and copper mineralization encountered in hole 20, drilled nearly mid-point between Zackly and Zackly SE, appears to be associated with quartz and sericite veining and alteration, indicators of a proximal to a porphyry system.
The Mars prospect, which brackets the northwest end of the corridor that is prospective for deeper porphyry mineralization, hosts another prominent magnetic anomaly PolarX would like to investigate further.
Broadly spaced sampling at Mars has outlined copper, gold, molybdenum and silver mineralization over a 2,000- by 1,500-meter area. Rock-chip samples collected here have returned up to 7.4 percent copper and 1.8 g/t gold.
This surface geochemical anomaly, coupled with a chargeability anomaly identified 100 to 150 meters below the surface of Mars, provides intriguing evidence of another potential porphyry copper-gold system about 3,000 meters northwest of Zackly.
An AU$3.9 million (about US$2.8 million) financing completed by PolarX in August is providing the Aussie explorer with the funds to accelerate exploration at Alaska Range, including further airborne and ground geophysics surveys; more detailed mapping and sampling at Mars; and additional resource expansion drilling at Zackly.
Gemini, roughly equidistant north of Zackly and northeast of Mars, is another porphyry target that PolarX would like to investigate further.
From Caribou Dome to Moonwalk
Besides Zackly and potential nearby porphyry copper-gold deposits, the Alaska Range property is rife with discovery targets.
Caribou Dome, located about 12.5 miles southwest of Zackly, hosts 1.6 million metric tons of JORC-compliant resource averaging 3 percent (107.8 million lb) copper that is amenable to open-pit mining; and 1.2 million metric tons of underground mineable resource averaging 3.2 percent (82.3 million lb) copper.
Soil sampling has shown that nearly the entire 22 miles covered by the Alaska Range property is mineralized to some degree with copper, silver and gold.
Moonwalk, a particularly gold-rich prospect at the northeast end of the property, is high on PolarX's list of exploration targets.
In 2011, Millrock collected 19 soil samples from the main zone of alteration at Moonwalk that averaged 1.15 g/t gold. The highest-grade soil sample returned 3.54 g/t gold.
Rock‐chip samples of quartz‐veins at this "Tintina-style" prospect returned assays up to 30.45 g/t gold.
These results, along with gold found in downstream sediment samples, indicate the potential of a large and high-grade gold system at Moonwalk.
PolarX took a closer look at this gold target with a late season mapping and sampling program.
"This heralds an exciting period for the company as it pursues several advanced targets, each of which could be part of a much larger district‐scale system," PolarX said.
PolarX Limited - ASX: PXX
Executive Director: Ian Cunningham
Managing Director: Frazer Tabeart
Executive Chairman: Mark Bojanjac
Suite 1, 245 Churchill Ave.
Subiaco, Western Australia 6008
Tel: 61-8-6465-5500
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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