HudBay Minerals Inc.
HudBay Minerals Inc. is being recognized for its Lalor discovery near Snow Lake, Manitoba. In turn, the company is recognizing Alan Vowles and Kelly Gilmore, the respective heads of HudBay’s geophysics and exploration teams, for their roles in the discovery.
In a 1980 report, Geological Survey of Canada geologist Don Sangster had outlined prospects for the Flin Flon greenstone belt in Manitoba and wrote that he believed “the largest deposit in the Snow Lake area is, as yet, undiscovered.”
With HudBay’s Chisel Lake mine in the Snow Lake area nearing the end of its reserves in the 1980s, HudBay began working to prove that Sangster’s view was correct.
It began a major exploration program. By 2002, well over a decade after it began, the company was moving to deeper and deeper parts of the basin and the exploration team agreed that it needed to develop an accurate method for targeting deep holes.
Project geophysicist Alan Vowles agreed to conduct a geophysical experiment that he had developed with former chief geophysicist Bob Frazer to see if they could detect the Chisel North mine 600 metres below the surface employing new technology.
Using Crone Geophysics’ deep penetrating EM system, Vowles plotted the layout of a large loop of wire for a survey that would carry the electrical current over a two-square-kilometre area above the mine.
He had a joking wager with Ed Yarrow, then HudBay’s vice president of exploration, that if the experiment showed that equipment was able to detect the existing mine, the company would invest in the necessary upgrades to do more testing.
Vowles hired local contractor Dave Koop of Koop Geotechnical Services to lay out the wire. Vowles says Koop is an adventurous, enthusiastic professional who thrives on the excitement of making new discoveries.
Although the zinc at Chisel and Lalor is not conductive, it is associated with minerals that are. As a result, Vowles anticipated that extraordinary measures would need to be taken to detect deposits significantly deeper than the 300-metre depth for which the equipment was certified.
With the instrument that detects conductive minerals set for the test, they threw the switch on the transmitter and the current flowed through more than 10 kilometres of wire.
But instead of the conventional practice of letting the receiver run for about 30 seconds to test to the technology’s proven depth of 300 metres, Vowles pushed it to a new level.
He left the current on to record thousands of readings while he and the team went for lunch! When they returned the readings confirmed the mine was clearly in evidence 600 metres below the surface.
The results meant that HudBay could use the technology to search for deep deposits all around their numerous mine sites in the Flin Flon area.
Working with project geologist Chris Roney, who has since left the company, Vowles identified two potential sites for the next test, one near an existing mine and the other spanning an area identified by senior geologist Jerry Kitzler at a depth of 1,100 metres.
In 2003, Vowles and Roney designed a plan for the next step. They laid out huge loops of even more wire to test an area more than 800 metres deep.
When the data were plotted on a map, the anomalies looked like two bull’s eyes at a depth of about 900 metres.
Later that year they drilled a single hole into the first of the targets.
Unfortunately, the copper and zinc grades in that single sample were not economic. But the technology had worked and they had proved they could find mineralization 800 metres down.
Economics and then weather conditions intervened and delayed more drilling. By 2007 senior geologist Craig Taylor was in charge of the project. He and Gilmore, who is now chief exploration geologist, were ready to drill the second target, again 800 metres down.
At last, four years after the anomalies were first identified, drilling resumed. The results were immediately obvious. The core box was unusually heavy and just by looking at the samples, the distinctive Lalor ‘Black Jack’ zinc was evident.
Since then drilling has continued steadily, and the company has subsequently announced its discovery of a new gold zone that significantly enhances the potential of the deposit.
So HudBay Minerals is continuing on its quest to track down the even bigger deposit that Don Sangster predicted.