Hamelin Gold: searching for an elephant in the Tanami Gold Province

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.

The elephant is touted as a noble beast worthy of our admiration.

In mining circles, the analogy of the elephant refers to the discovery of a world-class deposit.

As Hamelin Gold (ASX:HMG) Managing Director Peter Bewick succinctly states – “… it’s a metaphor for an absolute cracking discovery”.

Hamelin Gold is targeting mineral systems by undertaking systematic whole of project target generation work in the Tanami Gold Province in Western Australia. It’s also adopting new technologies and modern exploration techniques in the quest of its search.

The company has a landholding of almost 2,500km-square in the Tanami. The province is prospective for high-value, large-scale gold deposits – it hosts Newmont’s (NYSE:NEM) tier-one Callie operations, which has the same geology and key structures as Hamelin’s West Tanami Project.

With minimal modern exploration completed across its landholdings to date, Hamelin Gold’s focus in 2022 was to understand the regolith and structural controls of the region. In 2023 moving into 2024 its focus is on pathways to delivering ounces.

As the Managing Director tells Mining.com.au, it is here where Hamelin’s elephant search begins.

“We’re just very excited to have an absolute smorgasbord of opportunities where we can test some of the theories we’ve developed. We don’t expect them all to turn into orebodies, that’s not the way Mother Nature works, no, but when we’ve got multiple shots on goal, we’re hoping one goes in. That’s the theory.”

Trunks and tribulations

In corporate presentations, Hamelin Gold uses an X-ray image of an elephant to illustrate how it believes 2 important elements – gold and bismuth – ‘very intimately’ occur with the associated mineralisation in the Tanami but react differently when weathered.

Bewick explains: “When we’re talking about the weathering, we’re talking about the top 50m of the Earth, where elements and minerals will react differently. Some will be quite resistant or less mobile, so they stay where they should be or where they were originally, but others move around a lot and elements, for instance silver, is very mobile and gold is pretty mobile. It moves around and it gets leached and you can end up with a diluted plume or a weak washed-out signature where you did have quite strong gold mineralisation.”

The MD says bismuth on the other hand, appears to bond very quickly and does not wash away as rapidly as gold. The elephant X-ray analogy shows a broad, diffuse gold plume that’s been diluted and washed out broader than the original gold system.

“It gives you a bit of a larger footprint, but very subdued and low level. But the bismuth, the skeleton of the elephant, stays pretty well where it was when it was actually placed in the rock, so the weathering doesn’t move it around.

“But the bismuth, the skeleton of the elephant, stays pretty well where it was when it was actually placed in the rock, so the weathering doesn’t move it around”

What the scenario there is – you could go out and drill a hole across a gold deposit, such as a high-grade gold system, and you could end up with very strong bismuth numbers, which are easily above detection and very strongly mineralised. You could end up with this really subtle gold anomaly. And what we’ve just found by reviewing historical data is previous explorers have never looked at it this way. They’ve looked at the gold only and said, ‘Okay, that’s a low-grade gold number, we’re not interested, let’s move on to other areas’.”

Bewick adds in this environment, companies are in fact likely to uncover higher grade gold due to the rock forming at surface. Hamelin Gold’s deposits are under thin cover – where the rocks have been weathered, the gold signature is significantly lower but the bismuth is very strong.

“This tells us from looking at those plots of bismuth and gold that if you’ve got high bismuth, you probably did have high gold at some stage, but it’s just been diluted away. So, the bismuth is actually giving us a stronger indication of where the high-grade mineralisation might be …maybe more so than this diluted and washed-out gold signature. So that’s the elephant analogy.”

New target style for West Tanami

These indications have led Hamelin Gold to undertake a 10,000m aircore program with drilling planned at the Newkirk, Fremlins, Olsen, and Klinger prospects. A regional surface geochemical program is also in progress targeting the Sultan, Newkirk, and Far SW prospects.

An EIS co-funded drilling program at the Harkonan, Le Beau and Schultz prospects has commenced  with results from these programs expected in September / October 2023.

Interestingly, a single traverse of 3 RC holes immediately southeast of Fremlins has intersected a mafic-ultramafic intrusion with nickel-copper-PGE anomalism – now named the Hawkeye prospect. This anomaly was previously interpreted to be a folded dolerite sill similar to those commonly observed across the West Tanami. The RC holes were drilled across the anomaly to determine its source of the magnetism and map the basement geology.

Coarse disseminated sulphides were found here with up to 0.2% Cu, 0.1% Ni, and 0.6g/t 3E (Pd+Pt+Au) indicating the region is prospective for intrusion hosted Ni-Cu-PGE mineralisation.

The 3 RC holes intersected a thick, undeformed, differentiated mafic-ultramafic intrusion that contains broad zones of copper, nickel and PGE anomalism including 138m @ 231ppm Cu and 315ppm Ni from 12m to EOH in TLR0019.

Bewick says identifying a mafic-ultramafic intrusion hosting primary magmatic copper, nickel, and PGE mineralisation adds a new target style for the West Tanami.

His background in nickel and exploration dating back to the Western Mining days tells him – “this is super exciting”.

“It goes to show when you’re exploring in an area where you don’t have that known geology like you are exploring in an area of sand cover with very little previous systematic exploration work, anything can happen. What we targeted there was gold. We thought this was an interesting fold. One of the things we look for is folded geology with key structures running through it.

We targeted this area, put 3 holes across it and actually intersected something that hadn’t been recorded in the Tanami before – a nickel-copper-PGE sulphide mineralised mafic-ultramafic intrusion. Now, these are the sort of intrusions that host deposits like Nebo and Babel in the Musgrave Ranges that BHP just got hold of following the takeover of OZ Minerals.

“They’re very rare to find and to find potentially a suite of these just adds another really key element to our exploration strategy”

Now, it’s very, very early days. But it certainly says that these types of intrusions occur within the belt and now we’re actually targeting them. They’re very rare to find and to find potentially a suite of these just adds another really key element to our exploration strategy.”

A selection of samples has been submitted for multi-element analysis and petrological investigation to determine the host lithologies and confirm the sulphide assemblage observed within the Hawkeye intrusion.

Hamelin Gold is now conducting a project wide assessment targeting similar styles of intrusions across the West Tanami. Coincident magnetic and gravity geophysical anomalies are priority and a number of new undercover and unexplored targets have already been identified. A second new Ni-Cu-PGE exploration target generated through this review is the Klinger prospect, which will be drill tested in August 2023.

The company has also just completed a 4,500m aircore drill program around Hawkeye and the southern extensions of the Fremlins gold system with the drill rig now moving on to test its Newkirk gold prospect.

Bewick reiterates that to date the Newkirk gold occurrence remains completely untested and Hamelin Gold will be doing the first systematic drilling across the 1.5km long gold-bismuth soil anomaly.

“It’s probably got one of the best structural architecture, geochemical footprints, really strong bismuth in surface sampling, and it’s got a total of 4 drillholes that go down to 40m over a target that’s 1.5 kilometres long.

So, it’s a really large-scale footprint of what an elephant would look like. It’s a massive gold bismuth system. It’s just whether or not it contains high-grade mineralisation underneath it. And this is the first drilling, really down to bedrock, that’s ever been conducted on the project.”

Modern technological approach

As a company unafraid to test its theories and undertake exploration firsts, Hamelin Gold is also in the trial phase of an R&D project to determine if ultrafine soil analysis – a CSIRO-developed geochemical technique – is effective in the Tanami desert.

Following a series of orientation surveys, priority locations have been selected for soil sampling and analysis utilising the CSIRO-developed ultrafine technology. The survey areas were selected following a detailed targeting program and evaluation of historical drilling and orientation soil surveys.

Bewick says areas of thin sand cover and mix sand and residuum are likely the most applicable to apply this new technology. About 5,000 samples will be collected in the coming months with the initial trial program to be completed at the Sultan, Newkirk, Olsen, and Far SW prospects.

Assay results from these surveys will be reported in September or October 2023.

The MD adds, with a dearth these days of high-grade gold deposits and challenges in making multi-million-ounce discoveries it’s pertinent to embrace modern techniques and new technologies to track down that elephant.

“This will be the first time we’ve actually applied the ultrafine technology on a systematic broad scale sampling trial. We’ve targeted the northern extension of Newkirk and we’ve targeted the western and eastern extensions of the Sultan system, both of which we know are live systems and we really want to see how these ultrafines work.

“This could be the technology breakthrough that opens up significant parts of Australia which are under thin cover, where conventional geochemistry has not been that effective”

This could be the technology breakthrough that opens up significant parts of Australia which are under thin cover, where conventional geochemistry has not been that effective. It’s the sort of thing that you need to be thinking about now, because if you do exactly what previous explorers have done, again, it’s the definition of insanity – you’re not going to get a different outcome, you’re going to get the same outcome and you’ll go to the same locations and you’ll drill the same holes and you’ll find what they found.

You’ve got to really think about how we can open up what they call opening up the search space. So how can you make your area of effective exploration go from maybe a few square kilometres to maybe a few hundreds of square kilometres, where your new technology can take you into areas where previous conventional sampling took place”

Testing theories

Hamelin Gold is all about opening up its search space. The MD explains that as it continues exploration and tests various theories, the company is building a database of knowledge and understanding of how various minerals form.

“As we test these different theories, the more you understand about how mineral systems develop is that there’s actually a lot of fundamental similarities between many of the deposit styles that occur. They occur in areas of major structures, major key architectural intersections, large-scale earth processes occur at these really important horizons and then many different types of deposits can actually develop in those areas.

“…if you ever close your eyes to what could be out there, you’re really underselling for your shareholders”

So, we’re really keen from our targeting, what we call our early greenfields camp-scale targeting, you’re looking for the fundamental cracks in the earth’s crust that might be conduits for fluids and we don’t always know what sort of fluids come up those faults. And that’s why, if you keep your mind completely open, we are looking to find a multi-million-ounce gold deposit – that’s our company driver.

But if you ever close your eyes to what could be out there, you’re really underselling for your shareholders. I mean, you really have to keep your mind open to what deposits could occur. And the fact we had a nickel geologist on the rig when the Newkirk holes were drilled was really positive that he could recognise it straight away and understand what it meant. It meant that we assayed for a particular suite of elements and we’ve made a fundamental breakthrough. So, you’ve got to keep that mind open to what could be there.”

Sultan of Tanami

Hamelin Gold is also keeping an open mind to the opportunities that the Sultan gold prospect might offer. The 10km long Sultan shear zone remains a largely unexplored gold corridor. A surface soil sampling program has recently been completed over 6km of the corridor with both a LAG and Ultrafine sample to be submitted for analysis. Results from the soil sampling program and the re-analysis of the RC holes will be integrated before final design of a 1,500m EIS co-funded RC and diamond drilling program, which is planned for September or October 2023.

Sultan is situated in the northwest of the West Tanami project where diamond drillhole TSD0007 has intersected ‘high-grade’ mineralisation at the contact between a granitoid intrusion and a package of sediments and mafic rocks. TSD0007 was the first hole drilled completed beneath a +1km long gold and bismuth soil anomaly and was co-funded through the WA government EIS program.

Gold mineralisation here is hosted within a series of brecciated and deformed quartz veins with best results including 7.6m @ 3.2g/t Au from 326.2m, including 1.1m at 15.9g/t Au from 329.7m.

Bewick says this strong gold / bismuth association is remarkably consistent across the western half of the West Tanami project with a correlation co-efficient (measure of how closely 2 elements relate) in excess of 0.9, representing a very high relationship.

A visible approach undercover

Amid this backdrop, Hamelin Gold is positioning itself for a strong H2 2023 and held cash reserves of about $7.7 million as of 30 June 2023. The company is supported by significant shareholders such as gold miners Gold Fields (JSE/NYSE:GFI) and Silver Lake Resources (ASX:SLR) and has an experienced board and exploration team.

While the company is on track towards a pathway to deliver ounces, Managing Director Peter Bewick remains a realist in that even elephants come in all shapes and sizes and are found in different environments.

“Discoveries going forward are more than likely going to be undercover and being able to look in places like the Tanami…”

“I think the chances of a multi-million-ounce gold deposit sticking out of the ground in Australia is very limited. When you look back at the discoveries of the last, say, 20 years, you can see that they’re either getting deeper – people are finding 3 dimensional discoveries underneath many hundreds of metres of rock – or they’re typically finding them undercover. Sometimes that cover or benign rock, sand dunes, lakes, or river systems, they typically don’t contain any mineralisation at all, they’re completely devoid. If you sample that material conventionally, you’re going to get almost a zero result.

Discoveries going forward are more than likely going to be undercover and being able to look in places like the Tanami, where the cover thickness is sometimes a metre or it might be 5 metres. The really interesting thing that we’re finding is that we’re seeing sand being mixed with the basement material and you’re getting what’s almost like a super diluted surface position, but you’re seeing some evidence of mineralisation in that surface material.

So, we’re employing technologies that really focus on ultra-low level detection limits. It’s an example of what we’re trialling and it’s certainly not the only thing we’re looking at, but it’s one that we’ve gotten into first given the type of environment.”

Write to Adam Orlando at Mining.com.au

Images: Hamelin Gold Ltd
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Written By Adam Orlando
Mining.com.au Editor-in-Chief Adam Orlando has more than 20 years’ experience in the media having held senior roles at various publications, including as Asia-Pacific Sector Head (Mining) at global newswire Acuris (formerly Mergermarket). Orlando has worked in newsrooms around the world including Hong Kong, Singapore, London, and Sydney.