Margy Hawke: How Geologist’s whipsmart instincts helped unearth one of country’s richest copper-gold deposits

Margy Hawke dreamed of being an astronaut with NASA and one day piloting the Space Shuttle.

As a teenager growing up in rural Victoria, she won a scholarship to attend Space Camp at the US Space and Rocket Center, busking with friends in the Mildura mall to earn enough for the airfare to Huntsville, Alabama.

“I grew up wanting to be an astronaut - I was going to fly the Space Shuttle,” she said.

“I was going to be an astronaut, study maths and physics, study astrophysics, and somehow get myself to the USA and get into NASA.”

“Anyway, that was the ultimate dream, but I just discovered geology along the way.”

Shareholders in $5 billion Perth-based miner Sandfire Resources will be eternally grateful she did. Because Ms Hawke’s geological instincts helped unearth one of Australia’s richest copper-gold deposits, turning Sandfire’s share register into its own mining rich list.

Sandfire shares were flyblown and friendless in 2009 before Ms Hawke hit paydirt over the ANZAC long weekend at a remote prospect named after Dave DeGrussa, the Dongara driller and bush poet whose old tractor-mounted drill rig got the first sniff of the discovery – but who died days later before ever finding out.

The DeGrussa discovery was so bountiful it sent Sandfire shares on their own Space Shuttle-like trajectory, from 5c to more than $8 within a year.

The ever-modest Ms Hawke proffers that any geologist worth their salt could have followed the same geological clues which led her to the DeGrussa discovery.

However, the reality is, the girl from country Victoria who grew up wanting to fly to space was attentive enough to recognise those clues; intuitive enough to follow them; and persistent enough not to give up. Even if it meant putting her job on the line.

Ms Hawke had limited field experience when she started as a 23-year-old exploration geologist with Sandfire in 2007. Indeed, she knew nothing at all about gold exploration when she was dispatched on a 10-hour drive to the company’s grassroots Doolgunna property, about 150 clicks north of Meekatharra, on her first swing up north.

She was armed with a list of rotary air blast (RAB) drill targets passed on to her by outgoing Sandfire geologist Marian Skwarnecki. Her first on-site challenge was the terrain.

“We didn’t have a lot of resources out there, so some of the drill targets that had already been identified we couldn’t actually get to them, we’d have to clear a lot of trees out of the way,” she said.

Unfortunately for Ms Hawke, the delays in clearing vegetation meant the drill crew had to leave for another job before completing the Doolgunna drilling program. That’s when Mr DeGrussa and his partner Lynley Rattray came to the rescue, offering to convert their old tractor-mounted rig, which was doing regional vacuum drilling in the area, to drill the remaining RAB holes.

It was also when Dr Hawke unknowingly took her first steps on the ground above the DeGrussa discovery, oblivious to the riches buried beneath. Not because it had a highlighter pen through it on her target list, but simply because it was flat and accessible.

“It (DeGrussa) was just this big nice flat area - there was nothing there so we could just drive the rig straight on and drill it,” she said. “So that was one that we picked.”

“We drilled one line of drill holes across the top of that area and then did another line out to the west. And then we got rained out, so we packed up for the year and went home.”

They would be the last holes Mr DeGrussa ever drilled. “A few days after we got home we heard that Dave DeGrussa had passed away, pretty much the night he got home,” Ms Hawke said.

In January 2008, Sandfire received the assay results back from the laboratory from the Doolgunna drilling program. The holes Mr DeGrussa drilled before he died delivered the company’s best ever gold hits. The DeGrussa discovery had thrown out its first clue.

“We were only assaying for gold at that stage and we got the most consistent gold results we’d had across that (Doolgunna) project,” Ms Hawke said. “So we were onto something.”

“We needed to call it something - and we thought ‘let’s name it DeGrussa after Dave’.”

“Dave was a lovely guy, he taught me how to fix a split-rim tyre and used to quote poetry around the campfire at night. And his partner Lynley was quite happy with that. She said ‘we used to joke that maybe one day there’d be a mine named after us’.”

The results convinced the Miles Kennedy-chaired Sandfire board to send Ms Hawke back up to the newly-named DeGrussa prospect to supervise follow-up drilling programs, with the relatively modest aim of defining a mineable gold deposit.

It was then Ms Hawke started to question whether DeGrussa was, in fact, just a gold play, with the mineralisation concentrated in near-surface shear zones.

Indeed, from what she was observing from the drill core out in the field, the visible gold was actually hosted in an unspectacular looking reddish-brown “chert” rock formation.

“It (the chert) looks like nothing,” she said. “I mean, I can remember bagging some up and taking it back to the office and going ‘that’s the stuff.’ And everyone’s going ‘I don’t think so’.”

Ever curious, Ms Hawke started forensically sifting through all the historical exploration records from the Doolgunna project. One question stood out in her mind: why had the drill core and rock chip samples only ever been assayed for gold when there were known copper-rich volcanogenic massive sulphide (VMS) deposits in the area?

It was a question which could well have remained unanswered when the 2008 global financial crisis hit, sending a chill through Western Australia’s junior resources sector.

Battening down the hatches, the Sandfire board moved to retrench all but three of its staff – technical director John Evans, office geologist Allan Wynne and Ms Hawke.

Fortunately, Sandfire found enough in the kitty to have the latest Doolgunna drill core assayed for a broader suite of elements, rather than just gold. And when the results came back from the laboratory, it was a Eureka moment for Ms Hawke.

“So we did multi-element assays … and it (the drill core) was highly anomalous,” she said. “Your copper, your silver, your arsenic, antimony, lead, zinc - pretty much everything really. And they were all significantly elevated within the gold zone.”

“That kind of indicates to you that there’s a serious geochemical system.”

DeGrussa was now more than a sniff, with the cocktail of mineral riches in the drill core pointing to a motherlode lurking deeper underground.

“So it’s a case of ‘keep an open mind, we’re not just looking for gold here.’ You have the right tectonic setting here to have VMS deposits. You’ve got Horseshoe Lights, a known VMS deposit on the western side of the basin, you’ve got copper kicking around at Cashman’s, and an outcropping copper gossan with malachite and azurite at surface only 2km to the southeast of DeGrussa. So we know there’s copper around.”

Understandably, Ms Hawke was itching to get her boots back on the ground up at DeGrussa. However, she had to contain her excitement until she returned from a geological field trip she had enrolled in with the University of Tasmania to visit iron oxide copper gold (IOCG) and high sulfidation epithermal deposits in Chile and Peru.

“I mean, how often do you get to go to South America to see all these major copper mines?” she said. “I took leave and paid for it myself, took a loan out to do the course.”

“And I told them (the Sandfire board) they weren’t allowed to drill it till I got back.”

Serendipitously, the South American field trip gave Ms Hawke a glimpse from afar into the VMS treasure chest waiting to be unlocked back home.

“I was up in Peru at one of the high sulfidation mines and they showed us their geochemistry.” she said. “And it was a mirror image of what we’d been seeing at DeGrussa.”

“I already knew it was significant, but then to see a mine that had a very similar geochemical signature …”

“I told everyone I was going home to drill a mine.”

After returning to Perth, Ms Hawke drove up to DeGrussa in April 2009 in search of the VMS discovery she had visualised in Peru.

However, with only a 2,000m reverse circulation (RC) drilling budget to work within, she needed an early hit with the drill bit. It wasn’t to be.

Logged as DGRC086, Dr Hawke directed the first drill hole on a 60 degree angle hoping to jag a dipping depth extension of the surface chert gossan which had produced the rich multi-element geochemistry.

“We got it down to 60m, but there was a lot of water, it was really brecciated and fractured and the rods were jamming up,” Ms Hawke said. “So I opted to stop that hole, move on to the next one.”

Deflatingly, Ms Hawke lucked out with the next hole as well, and those which followed. The chert didn’t appear to proceed to depth as expected, with the drill bit all too often bottoming out in dolerite.

Things looked ever more ominous when the drill rig broke down on the last planned hole, DGRC100.

It was hot, dusty and approaching beer o’clock on Good Friday, April 24th, 2009. Everything was pointing towards packing up and going home for the rest of the ANZAC long weekend.

However, rather than calling it quits, the drilling crew drove to Kalgoorlie to get the parts needed to fix the rig – a round trip of some 14 hours. By the Monday public holiday, the rig was back in working order, the drill rods spinning to finish off DGRC100.

When the drill core from that hole showed no encouragement, the DeGrussa story – and perhaps Sandfire itself – could well have ended right there and then. The bartender at the Last Chance Saloon was lining up the final round of drinks.

However, Ms Hawke then made a captain’s call which changed the course of history. Acting on a hunch, she told the drillers to go back to the first abandoned drill hole, DGRC086.

“I had a sneaky feeling about that first hole that we didn’t get all the way through the chert, that failed,” she said. “I thought ‘I’d really like to do just one more hole.’ If we drill it vertically, the hole’s less likely to collapse and we’ll be able to get through and see where it (the chert) has gone’.”

With that, Ms Hawke rang her boss John Evans back at Sandfire’s office in West Perth for approval to drill an extra hole. “No one answered,” she said, “So I just did it.”

“I was still under budget on metres and I just figured the cost of drilling that hole would have been the same as sending the rig away and then getting it back again.”

It was then the sniff turned into smoke signals.

Unlike that signaling the anointing of a new Pope at the Vatican, there was nothing spectacular about the plume of smoke-like white dust billowing from drill hole DGRC101 as it entered a zone of barren clay on its vertical descent.

But at a depth of 98 metres, the colour of the dust changed. And with it, Sandfire’s eternal fortunes.

DGRC101 had pierced the copper-rich cap of the DeGrussa massive sulphide deposit. And as if awaiting discovery, it was thoughtfully sending smoke signals to those on the surface to let them know.

“At 98 metres, the dust on the rig went black,” Ms Hawke said. “There was a lot of water as well … and the drillers were struggling to lift the bags as they dragged them away from the rig.”

“You put your hand in it (the sample bag) and it’s just like metallic paint. I thought ‘what the?.. it’s really heavy … it’s got to be something’.”

“I was like ‘I’ve never seen this, it can’t be sulphide, what else could it be? Could it be biotite - that’s shiny. I mean, no one ever sees this, maybe it’s something else?’

“So a few metres of that and then we were down into the chalcopyrite and pyrite zone as well. That hole went to 144m before there was just too much water.”

And I’m just in a state of like ‘I think this is good, but is it really? Am I blowing the budget for nothing? Am I interpreting this correctly?

At the risk of blowing the budget, Ms Hawke had only one thing on her mind: drill, baby, drill.

“The drill crew also were happy to keep drilling – the global financial crisis meant there wasn’t much work out there,” she said.

“So we stepped out 20m to the north and went down again. We started getting malachite and azurite and native copper in the clays - and these are in zones where I’m just like ‘shouldn’t we have been seeing this before?’

“Then, on further drill holes over the next few days – I think I put in about five or six - we pulled up to 100m of just massive sulphide down-hole from about 100m.”

“And I’m just in a state of like ‘I think this is good, but is it really? Am I blowing the budget for nothing? Am I interpreting this correctly?”

Either way, she decided it would be a wise career move to try again to get hold of Mr Evans back in Perth. So she took a photo of the sulphide rock chips on her Nokia 2700 cell phone and drove up a nearby hill where she could latch onto the Plutonic gold mine’s mobile tower to send the picture through to Sandfire’s office geologist, Allan Wynne.

“I had a few of these little chips of sulphide, took a picture of it, stood on the roof of the four wheel drive, sent this off to Allan in the office and said ‘got a lot of sulphide, can you get John to call me’.”

“John called me back that night after he got back from his field adventures and said ‘I hear you’ve hit massive sulphide?.’

“He asked ‘is that 5-10% massive sulphide? And I said ‘no, it’s more like 95-100% massive sulphide’.

“There was silence on the end of phone. So I said ‘I’ll just keep drilling until I can’t find it anymore’.”

Once the drilling was finished, Ms Hawke drove back to Perth with her precious cargo of drill samples, which were dispatched to the assay laboratory post-haste.

The assay results, announced to the stock exchange on 18 May 2009, proved Ms Hawke had indeed made a fabulously rich copper-gold strike.

And with that, Sandfire instantly became the hottest stock on the Australian sharemarket. In Poseidon-like fashion, the former penny dreadful quickly became a billion dollar market darling.

By 2012, just three years after the discovery, Sandfire was already mining DeGrussa’s riches, filling the boots of its shareholders with dividends.

By then, Ms Hawke had left the company. After such a hectic couple of years, she needed a change of pace.

“I just thought I want to do something else for a while,” she said. “So I went travelling a bit, I went and did a PhD down in Tasmania on the DeGrussa deposit. I just kind of stepped out of the industry for a while, which was a nice change.”

And while she still hasn’t flown the Space Shuttle yet, her love of flying saw her go on to secure both commercial helicopter and private fixed-wing licences.

Reflecting on her role in the DeGrussa discovery, Ms Hawke said the key factor was simply sticking to “a methodical procedure” to follow the geological clues.

“But at the same time, I knew those rocks pretty well out there – I’d drilled out there for two years, walked around it a lot, walked to the top of most of the hills. And if you know the rocks well, you’re going to be able to see when there’s something different - and DeGrussa was certainly different.”

“The geochemical anomaly comes right to the surface, I just think it’s partly luck that no one did any detailed work out there to start with. And, how do I put this, I think I’m a decent geo as well and I’m going to keep on persisting if I think something’s there.”

“If DeGrussa hadn’t been near to the surface, I don’t think anyone would have found it, it’d still be there.”

Post her PhD, and after several years of consulting work around Australia and Africa, the lure of finding another DeGrussa-like discovery led Ms Hawke to join Rio Tinto’s project generative team.

These days, she said exploration geology was no longer as much of a blokey industry as it was when she started out almost two decades ago, and her advice to budding young geologists was “do it if you love it.”

“I spoke at Kent Street High School the other day about my career and the first slide that I showed them was a picture of me in my first week at work in the Kimberley absolutely covered in dirt.”

“Do what you love. If you don’t love it, don’t do it. Geology is a lifestyle, if you’re really passionate about geology, love travelling and exploring, then you’ll be fine.”