Exploring for Alaska-type platinum metals
State is prime hunting ground for industrious precious metals Critical Minerals Alaska 2020 – Published October 29, 2020
Last updated 12/23/2020 at 4:32am
The six platinum group elements – platinum, palladium, rhodium, ruthenium, iridium, and osmium – have one foot firmly planted in the realm of precious metals while the other is firmly established in the industrial sectors.
While being amongst the rarest metals on the planet already makes PGE's highly valued for jewelry and bullion, their applications in the automotive, petrochemical, and electronics industries are catalysts that drive the price of these industrious precious metals even higher.
"PGEs are indispensable to many industrial applications but are mined in only a few places," the U.S. Geological Survey inked in a 2017 report on platinum group elements. "The availability and accessibility of PGE supply could be (and have been) disrupted by social, environmental, political, and economic events."
It is this combination of industrial need and potential disruptions to supply that land PGEs firmly on the USGS list of 35 minerals and metals critical to the United States.
Alaska is home to two historically significant PGE mines and is prime hunting grounds for future domestic sources of these industrious precious metals.
PGEs – also referred to as platinum group metals or PGMs – are prized jewelry metals due to their shimmering white color, durability, and resistance to tarnish.
Furthering their role as precious metals, platinum, palladium, and rhodium are minted into coins and bars for investment purposes.
The precious value of these metals is pushed to greater heights by their corrosion resistance, durability, electrical stability, and their ability to hold up to high temperatures.
"The leading domestic use for PGMs was in catalytic converters to decrease harmful emissions from automobiles," USGS wrote in its Mineral Commodity Summaries 2020. " Platinum-group metals are also used in catalysts for bulk-chemical production and petroleum refining; dental and medical devices; electronic applications, such as in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors; glass manufacturing; investment; jewelry; and laboratory equipment."
The most valued of these is rhodium, a sliver colored metal that is extremely resistant to corrosion and highly reflect – qualities used to add luster to jewelry, mirrors and even search lights.
As cherished as it is for aesthetic and reflective qualities, the largest use for rhodium is as a catalyst to scrub carbon monoxide, hydrocarbons, and nitrous oxide from the exhaust of automobiles and petroleum refineries.
The combination of beauty and work ethic ranks rhodium among the most valued metals on the planet, selling for more than US$10,000 per ounce in September.
It is platinum and palladium, however, that are most commonly used as a catalyst to reduce harmful emissions from autos. The auto sector has shifted its preferred catalytic metal depending on price.
"Palladium has been substituted for platinum in most gasoline-engine catalytic converters because of the historically lower price for palladium relative to that of platinum," USGS penned its annual Mineral Commodity Summaries.
This shift has driven the price of palladium to around US$2,200/oz at the time of this writing, while platinum prices are at around US$900/oz.
"Since October 2017, the average price of palladium has been higher than that of platinum, which had not been the case previously since 2001," according to the USGS.
Iridium sells for around US$1,650/oz; osmium is holding around US$400/oz; and ruthenium is roughly US$270/oz.
With only one PGM mining operation in Montana, the United States relies on other countries – primarily South Africa – for roughly 64% of its platinum and 32% of its palladium.
A special category of PGM-hosting deposits that partially derive their name from Alaska – Ural-Alaska-type ultramafic complexes – hint at the Far North State's prospectivity for this group of industrious precious metals.
These PGM prospective intrusive bodies can be found along Wrangellia Composite Terrane – a series of geological assemblages that span a 1,250-mile-long arc that sweeps across the breadth of the state.
From the Southeast Alaska Panhandle, the Wrangellia Terrane arcs through southwest Yukon and back into Southcentral Alaska, and then onward into the southwest part of the state – a microcontinent considered to be prime hunting ground for the suite of platinum metals.
The most advanced PGM deposit along the Wrangellia Terrane is Nickel Shäw (formerly known as Wellgreen) in the Yukon.
Situated about 60 miles east of the Alaska-Yukon border, Nickel Shäw hosts roughly 5.3 million oz of platinum and palladium, 1.9 billion pounds of nickel, 1 billion lb of copper, and 107 million lb of cobalt in the measured and indicated resource categories.
Nickel Creek Platinum Corp. is currently working on the optimization studies as it considers developing a mine at Nickel Shäw.
There are intriguing signs that similar PGM-nickel-copper-cobalt deposits could be lurking in the Alaska portion of the Wrangellia, such as the Man property about 250 miles northwest of Nickel Shäw.
With holes cutting up to 81 meters averaging 0.315 g/t platinum-palladium-gold, 0.17% copper and 0.25% nickel in the Eureka zone at Man, indicate the great PGE potential of this property.
Pure Nickel, the former owner of Man, said that a review of drilling shows that all holes that cut the Eureka zone encountered disseminated sulfide mineralization with strikingly similar grades along 4.5 miles of the central part of Alpha.
The PGE and nickel potential of this section of the Wrangellia Terrane stretching across Southcentral Alaska has attracted the attention of global miners such as Australia-based MMG Ltd.
In 2013 and 2014, MMG investigated three large blocks of state of Alaska mining claims that follow an arc south of the Alaska Range.
These claim groups include Amphitheater, which borders the Man property to the south and west; Butte Creek, located about 40 miles southwest of Amphitheater; and Talkeetna, a block of claims roughly 30 miles further along this PGE prospective arc.
The Peninsular Terrane, a subsection of the Wrangellia Composite Terrane that stretches along the Chugiak Mountains in Southcentral Alaska, is also known for its PGE potential.
New Age Metals Inc. has advanced early staged exploration at Genesis, a 10,240-acre, drill-ready platinum group metal project in the Peninsular Terrane.
Situated along the Richardson Highway about 75 highway miles north of the deep-water port city of Valdez, Genesis is an under-explored palladium-platinum-nickel-copper property with great infrastructure.
Sampling of one drill-ready reef style target at Sheep Hill on the Genesis property returned up to 2.4 g/t palladium, 2.4 g/t platinum, 0.96% nickel and 0.58% copper.
Bernard Mountain, situated about 4.7 miles (7.5 kilometers) west of Sheep Creek, hosts a separate style of chromite mineralization containing up to 2.5 g/t palladium and 2.8 g/t platinum.
Despite this surface PGE-copper-nickel mineralization, no drilling has ever been carried out on this project that is less than two miles from a paved highway and an electric transmission line.
A 2019 program at Genesis, which included the interpretation of NASA Landsat imagery and reinterpretation of previously flown geophysical surveys, identified 23 exploration targets across the Genesis property.
The imagery and geophysical data indicate the mineralization at Sheep Hill extends for at least 2,000 meters, more than double the previously identified 850 meters, and is open under alluvial cover in both strike directions.
New Age Metals Chairman and CEO Harry Barr told Mining News that this ease of access, superb infrastructure – along with the PGE-nickel-copper mineralization right at surface – makes Genesis the type of property that major mining companies are looking for.
Goodnews for platinum
For an explorer seeking extremely rare PGEs, a town by the name of Platinum seems to be a good place to start.
About 120 miles south of Bethel, Platinum is in the Goodnews Bay region of Southwest Alaska, an area that was the primary domestic source of platinum in the United States for about five decades.
Yup'ik residents of the area, Walter Smith and Henry Wuya, first discovered platinum in the streams draining Red Mountain in 1926.
This discovery led to a claim-staking rush followed by several small-scale mining operations. Eventually, Goodnews Bay Mining Co. consolidated the platinum producing claims in the area and operated a bucket-line dredge in the area from 1937 to 1978, accounting for most of the roughly 650,000 oz of platinum that has been mined from the streams in this area.
High PGM prices have sparked renewed interest in the Goodnews Bay placer deposits over the past decade. This interest has included using modern equipment and techniques to recover platinum left behind by the dredge.
In addition to additional PGMs remaining in the streams of this platinum-producing area of Southwest Alaska, USGS geologists believe there could be significant marine placer platinum deposits just offshore.
In addition to what might be found in the ocean downstream from this historical placer deposits in Goodnews Bay, there has been interest in finding the lode source upland from Salmon River and its platinum-bearing tributaries.
A Ural-Alaska-type ultramafic body is believed to be the lode source of this historical placer production.
Red Mountain is considered the likely source of the placer platinum deposits in the Goodnews Bay area.
Exploration at Last Chance, a prospect at the head of a platinum bearing creek draining Red Mountain, has turned up some promising results. Rock samples taken from an outcrop at Last Chance returned assay results up to 2.27 g/t platinum. Geologists have also discovered platinum- and palladium-enriched veins there.
While Goodnews Bay is known for its historic platinum production, the past producing Salt Chuck Mine on Prince of Wales Island in Southeast Alaska was a top palladium producer in the United States until being shuttered during World War II.
From 1915 to 1941, Salt Chuck produced some 300,000 metric tons of ore averaging 0.95% copper, 1.96 g/t palladium, 1.12 g/t gold and 5.29 g/t silver, according to U.S. government summaries (1948).
Though Salt Chuck was never put back into production after its wartime shutdown, a 7,000-meter-by-1,600-meter mafic-ultramafic igneous complex is prospective for the metals recovered at the bygone operation.
This site, however, has been on the U.S. Environmental Protection Agency Superfund list for the past several years.
Superfund – the informal name for the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) – is a federal program designed to fund the cleanup of contaminated sites.
With Superfund activities at Salt Chuck complete, EPA is now seeking ideas to return the site to productive use through its Superfund Redevelopment Initiative. Several companies and individuals hold mining claims over and surrounding the historic palladium mine.
The entire Southeast Alaska Panhandle is prospective for PGM deposits similar to Salt Chuck.
One such prospect is Duke Island, located about 70 miles southeast of the historic palladium mine.
Group Ten Metals, the company that owns the Duke Island project, said the abundance of copper-nickel-PGE sulfide mineralization found there is unlike any known Ural-Alaska complex.
Outcrop grab samples have returned values up to 2.8% copper, 0.25% nickel and more than 1 g/t PGE.
Of the four large zones of copper-nickel-PGE mineralization identified at Duke Island, only one, Marquis, has been drilled.
None of the 16 holes are thought to have been drilled deep enough to tap the contact with a feeder zone where the highest grades of mineralization at Duke Island is believed to occur.
Brady Glacier, a significant nickel-copper deposit at the north end of the Southeast Alaska Panhandle, also carries a significant amount of platinum group metals.
Historical drilling at Brady Glacier outlined 100 million tons of rock averaging 0.5% nickel and 0.3% copper. Roughly 250,000 oz of PGEs are estimated to be included in this drilled resource area.
Though Newmont officials deemed Brady Glacier the largest copper-nickel deposit in the United States during the company's investigation of the deposit in the 1970s, this PGM-enriched deposit is within the Glacier Bay National Park and Monument.
While this locale likely precludes any development in the foreseeable future, the rich deposit speaks to the PGE potential along the entire Southeast Alaska Panhandle.
New hunting grounds
While the Wrangellia Composite Terrane is considered the best place in Alaska to hunt for platinum group metals, a number of prospects exist beyond this belt.
The Angayucham Terrane, a belt of rocks found along the northwestern slopes and south of the Brooks Range in Northwest Alaska is another area state and federal geologists consider to be highly prospective for PGMs.
Misheguk Mountain, a chromium occurrence about 45 miles east of the Red Dog Mine, is an Angayucham Terrane prospect with significant PGEs.
Assay values of 4.3% chromium and 0.22% nickel were obtained by the U.S. Bureau of Mines over a 50-foot sample reported in 1978. Individual samples collected from Misheguk Mountain returned up to 4.2 g/t platinum, 4.7 g/t palladium, as well as small amounts of rhodium, ruthenium, iridium, and osmium.
From the Seward Peninsula in western Alaska to the Fortymile district adjacent to the Yukon border, small amounts of placer platinum have been recovered as a by-product of gold mining. These anomalous occurrences underscore the potential of discovering PGMs across Alaska's vast gold-producing districts.
The Valdez Creek Mining District, about 65 miles southeast of Fairbanks, is one such region. According to a 1988 U.S. Bureau of Mines report, concentrates from 52 alluvial samples collected from placer gold streams in the district contained measurable quantities of PGMs.
One sample from Gold Creek contained 3.1 g/t platinum; another sample from Tyone Creek measured 4.1 g/t platinum and 0.28 g/t ppb palladium, while a sample from Fourth of July Creek returned 2.5 g/t platinum.
No mafic or ultramafic rocks – the igneous rocks typical to Ural-Alaska-type ultramafic complexes – are known to exist in many of these areas where PGMs are found. A geological model that explains these hints of platinum metals could open new areas of Alaska to hunt for this group of precious, industrious, and critical metals.