This article is a sponsored feature from Mining.com.au partner Hamelin Gold Ltd. It is not financial advice. Talk to a registered financial expert before making investment decisions.
Bismuth is considered to be a rare and beautiful metal.
It has a pinkish hue and a rainbow-like oxide layer that gives it a similar appearance to a gemstone. But it is not bismuth’s good looks that has the team at Hamelin Gold (ASX:HMG) excited.
The company is adopting a modern approach to a prospective yet largely underexplored landholding in the Tanami Gold Province in Western Australia. The identification of the remarkable relationship between bismuth and gold in the Tanami has delivered a powerful new exploration tool to the young team.
Hamelin listed on the Australian Securities Exchange (ASX) in November 2021 with its primary asset being a landholding of 2,500km-square in the well-endowed Tanami Province, which is prospective for tier-one gold and rare earth element deposits.
The Tanami also hosts Newmont’s (NYSE:NEM) 14 million-ounce Callie Operations. As Hamelin Gold Managing Director Peter Bewick tells Mining.com.au, the company’s flagship project is a belt-scale greenfields opportunity hosting the same geology and key structures as Callie.
Uniquely, Hamelin’s landholdings have had minimal modern exploration completed to date.
Applying innovative thinking
Bewick explains that Hamelin is taking a contemporary exploration strategy to this well-endowed but underexplored region. He says the area is dominated by shallow, ineffective historical drilling and as such, the company is deploying new techniques and applying innovative thinking to better understand the regolith and structural controls of the area.
“Hamelin believes the West Tanami Project has the potential for the discovery of multi-million ounce gold deposits similar in nature to the giant Callie Gold Operations owned by Newmont located 100km to our east. We have a strong portfolio of quality large-scale gold prospects and success in the West Tanami would see the company grow rapidly.”
“Hamelin believes the West Tanami Project has the potential for the discovery of multi-million ounce gold deposits similar in nature to the giant Callie Gold Operations”
The junior exploration company started an innovative R&D program in 2022 to evaluate the effectiveness and applicability of novel surface geochemical techniques to its gold exploration.
A second study investigated the mobility and behaviour of potential pathfinder elements in the deeply weathered and leached regolith profile in the West Tanami. While arsenic has been the preferred gold pathfinder element of previous explorers, Hamelin’s review of available geochemical data demonstrates that arsenic in fact correlates ‘very poorly’ with gold mineralisation in the region and does not offer a reliable or accurate indicator of gold.
The MD says analysis of all multi-element geochemical data instead identified that primary gold mineralisation in the West Tanami has a ‘remarkably’ high correlation with bismuth. The first test of the bismuth – gold theory was at the Sultan prospect that delivered a ‘high-grade’ gold discovery in the first hole, fortuitous or maybe the Hamelin team are on the right path.
“The Sultan prospect was the first test of our new concept that areas of depleted gold and strong bismuth anomalism could represent the footprint of a major gold system along a previously untested granite contact. We were limited in where we could drill due to existing access so the hole location was fixed and probably not ideal. Having said this, we did intersect high-grade gold along strike from the high bismuth anomalism thus confirming our hypothesis and opening up this new gold corridor.”
The single diamond hole drilled at Sultan in late 2022 was drilled to evaluate a more than 1km long coincident gold–bismuth anomaly located on a previously untested granite contact. Drillhole TSD0007 intersected a veined and altered shear zone returning ‘high-grade’ results 7.6m @ 3.2g/t Au from 326.2m, including 1.1m @ 15.9g/t Au from 329.7m.
This mineralised intersection remains open along strike and up-dip and highlights the potential for a new mineralised corridor at Sultan. The MD notes that re-interpretation of the structural setting of Sultan has highlighted a significant possible extension to the gold corridor further to the east into an area of no previous exploration activity.
Pathfinder to gold
Bewick says: “Previous explorers focused on areas of outcropping high-grade gold veins and along interpreted dolerites. Areas of cover where gold signatures are subtle and granitic contacts were not targeted by previous explorers as these positions were not considered as prospective. Hamelin’s early work has proven this assumption to be incorrect.”
During the recent work undertaken by the company, new interpretation of geochemical and geophysical data has identified multiple camp scale gold targets in the 100% owned West Tanami Project. Hamelin discovered that only 30% of all surface geochemical and drillhole samples in the company database have been analysed for bismuth, the pathfinder to gold in the Tanami.
So, why is this an exciting proposition for the company?
The MD explains that in the West Tanami, Hamelin has now proven to some degree that bismuth has an extraordinarily strong correlation to gold. Moreover, bismuth is more resistant to leaching, meaning a strong bismuth signature at surface is a close proxy for a strong gold signature.
bismuth is more resistant to leaching, meaning a strong bismuth signature at surface is a close proxy for a strong gold signature
“Every element reacts differently when weathered. In the Tanami, weathering profiles are deep and intense. In this environment gold is leached and the surface expression is weak – especially if diluted by sand. In these environments pathfinder elements are often targeted especially if they are more resistant to leaching and provide a direct indicator of gold mineralisation.”
Given Hamelin Gold’s 2,500km-square tenure in the region, from a mining and investment proposition, this unique bismuth-gold correlation discovery in a province prospective for tier-one gold deposits is quite the find.
The MD notes: “Holding a commanding land position in a high-endowed gold province and emerging REE district is a fabulous asset for a junior explorer. With this tenement position we have multiple exploration opportunities and the potential to discover a new field and significantly re-rate the company.”
The business of bismuth
However, Hamelin still has a lot of work and testing to undertake. Limited analysis of bismuth distribution has historically been completed. Bewick says given the new realisation of the critical association of gold and bismuth in the Tanami, Hamelin has interrogated the historical surface and drillhole sample dataset identifying significant, kilometre-scale footprints of strong bismuth anomalism that have been either ignored or unrecognised by previous explorers due to the subdued near-surface gold signatures.
The company now considers these areas high-priority gold targets.
The MD says at the Newkirk prospect, the strongest of the bismuth anomalism is located in the northeast of the anomaly. No bismuth analyses have been completed on the LAG samples taken further to the east and north of this line and as such this anomaly remains open.
The Olsen target is a coincident geochemical and geophysical anomaly that occurs in a region containing significant areas of sand and sheetwash cover making the coherent low level gold anomaly of particular interest, albeit this area was never analysed for bismuth. Like so much of the project, limited follow up work was conducted by previous explorers at Olsen with only a handful of 50m deep RAB holes completed on 2 separate sections.
The Olsen target will initially be tested with a series of aircore drill sections drilled to the top of fresh rock with drilling planned to be completed in June or July 2023.
A rare and beautiful approach
While there are more than 184 companies in the gold sub-industry listed on the ASX, according to Geoscience Australia, the precious metal is a very rare mineral making up only about three parts per billion of the Earth’s outer layer.
Data shows that in 2021, Australia was the second-largest gold producer with 330 tonnes annually and by far held the most reserves with 11,000 tonnes representing about 20.4% of global reserves. China was the largest global mine producer at 370 tonnes annually, which was about 12.2% of global mine production.
However, as Hamelin Gold’s MD tells Mining.com.au, while there is a plethora of gold miners on the Australian bourse, it’s not always a guarantee that an exploration company will successfully develop a gold deposit.
Should Hamelin’s modern and unique exploration technique using bismuth as a pathfinder to gold mineralisation prove successful, it would certainly be a rare and beautiful story.
Write to Adam Orlando at Mining.com.au
Images: Hamelin Gold Ltd
