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‘From Perth. I’ve been in Australia since I was six. My Dad’s Finnish and Mum’s a Scot. That probably explains both my odd accent and unusual surname.’
‘Ah! I see you’re a geologist! Alec moved the conversation away from the personal and pointedly looked at the familiar orange-yellow cover of the Journal of Geological Society of Australia that Petri had politely put down when the others joined the table. ‘That’s a coincidence, so am I! I’m a lecturer in the geology department but I don’t think I’ve seen you in there.’
‘Probably not. I’ve only been here a few days and most of the time stuck in the library or in Dr. Fleming’s office.’
‘So, what are you doing over here?’
There was a spark of immediate rapport between the two men and the conversation flowed easily as they exchanged information about their relative interests. Shelley smiled to herself, ‘so typical of men! As soon as they find a common interest they chat on as if I don’t exist.’
Being the secretary in the economics department meant that much of the geological discussion went right over her head, although she did follow the conversation as much as she could and was interested in learning. Her eyes moved from one man to the other as they animatedly discussed their pet projects.
As if reading her thoughts Alec turned to her and apologised. ‘Sorry, Shelley. I hope you don’t mind us talking shop.’
‘No, no, not at all. I actually find it quite interesting.’
‘I’m really involved in an exploration program out west,’ Petri explained. ‘Gold from the greenstone belts must have gone somewhere over the millions of years of erosion, and we all know how rich the Kalgoorlie area has been —’
Shelley interrupted the flow. ‘I’m only a secretary but if you explain a bit I can be included in your select group of geologists. So, what are the ‘greenstone belts’?’
‘Sure, I apologise. We didn’t mean to be rude!’ said Petri.
‘And try to put all this in layman’s terms so I’m not totally left out of it!’
‘Sure. I’ll do my best. If you don’t follow, because we geos naturally slip into jargon, just stop me and I’ll try to explain.’
Shelly smiled. ‘Thanks, I’d appreciate that.’
Petri continued. ‘In WA the rocks that are host to nearly all of the gold mines are called greenstones. They’re all green because of the minerals that make them up. They’re really ancient volcanic rocks, some of very unusual compositions, and are probably about three billion years old.’
‘Did you say three billion, or million?’
‘Billion. Three thousand million.’
‘Wow. I didn’t realise there were rocks that old.’
‘Oh, yes. And there are even older rocks in the world. Anyway, that means they have been exposed for a very, very long time. In the Tertiary Period, that’s only about thirty million years ago, Australia was further south and the climate much wetter than today. During that time large rivers flowed inland, parts now desert and they flowed across the greenstone belts.’
Shelley nodded as he spoke. He had a gentle voice that, with his unusual accent, made him very appealing. She was interested in what he had to say but she found herself wondering what sort of a man he was. As he explained further her mind was drifting slightly to the person rather than to what he said.
‘We call that the Tertiary drainage pattern. You can still see where they flowed if you link up all the present day salt lakes. They’re not really lakes, just saltpans, but link them up on a map and hey presto! You can see the old river patterns. Well, just as today we get gold in placer deposits—’
‘I know what they are,’ interrupted Shelley suddenly picking up on the conversation. ‘That’s when heavy minerals, like gold, are concentrated in flowing rivers as the water washes away the lighter materials. My uncle used to go panning for gold in some of the creeks in the Victorian goldfields. He even found a couple of nuggets.’
‘Correct.’ Alec smiled affectionately at her. ‘We might even turn you into a geo at this rate!’
Petri continued. ‘Well, anyway, I’m working on a program with a small mining company looking to see if there is some way they can access the gold deposited at placers in those Tertiary channels but without panning or conventional mining. You may have heard of Spinifex Exploration N.L?’
‘Oh! yes, Spex. It’s been in the news lately because of some new nickel discoveries near Kambalda. Is that the one?’ asked Alec.
‘Yeah, that’s us.’ Even though on contract and not an employee Petri tended to think of himself as so much a part of Spex that he used ‘us’ when referring to the work he did with the company. ‘The idea is to pump down a cyanide-based solution in one area, let it soak down through the channel, dissolve any gold present, then pump it up further downstream and precipitate out the dissolved gold!’
‘Isn’t that environmentally dangerous, though?’ asked Shelley. ‘I mean cyanide is pretty poisonous. Won’t it affect the ground water and poison it?’
‘That’s not really a problem in that area. Firstly, the ground water is so salty that it can’t be used for any purpose, irrigation or stock. It is thousands of times more salty than sea water and not just salt as in sodium chloride but all sorts of other salts like magnesium and potassium —’
‘Now, don’t get too technical for me,’ interrupted Shelley with a smile.
‘Okay. I was just going to say … now what was I going to say?’ Shelley’s smile was disarming and Petri momentarily lost the thread of his explanation. ‘Oh, yes. I was going to add that once the pregnant liquor is pumped up to the surface, the gold dissolved in the cyanide solution can be recovered and the cyanide solution recycled.’
