Despite occupying one of the most mineral-rich areas of the world, large swaths of the Sudbury Basin have remained unexplored.
Dan Farrow, the Sudbury District geologist with the Ontario Geological Survey, said Vale and Glencore hold a large number of patented mineral claims, for tracts of land in the Sudbury Basin only they can explore.
Because both companies have a number of productive mines in the region, they haven't yet bothered to explore many of those regions.
The patented claims – which lease mineral rights to the companies in question – are in an area geologists refer to as the eruptive.
Researchers estimate a meteor made impact more than 2 billion years ago with what is now the Sudbury Basin.
The impact left a crater 200 kilometres in diameter, and brought molten magma beneath the Earth's crust to surface.
The prevailing theory, said Farrow, is that the magma was rich in minerals, such as nickel and copper. When it hardened, it formed the mineral deposits that have defined the Sudbury Basin.
Sudbury's mining giants Inco and Falconbridge – and later Vale and Glencore, respectively – jumped on rich contact deposits of solid ore.
“That's what Inco and Falconbridge mined for years because it was so easy,” Farrow said.
Smaller companies like FNX had to be more creative and mined footwall deposits – the rock on the underside of the mineral vein – that had fewer large solid chunks of minerals.
But the footwall deposits, while more difficult to mine, proved to be rich in copper and platinum group elements, which are important components for catalytic converters in vehicles and fuel cells.
FNX proved successful enough to attract a merger with Quadra, and a later buyout by Polish mining giant KGHM International.
For Farrow, one of the most exciting mining companies exploring the Sudbury Basin today is Wallbridge Mining Company Ltd.
“Wallbridge is a Sudbury success story, because they're the third-largest property owner,” he said. “They're just a pleasure to have here because they work so hard and are very thorough.”
Wallbridge opened its Broken Hammer open-pit mine earlier in the year.
The mine is expected to produce around 195,000 tonnes of in-pit copper, nickel and platinum group elements.
The company also plans to conduct exploration activities on its Wisner properties, which surround the Broken Hammer deposit. Geophysics and drilling have already been initiated on those sites.
While the mining sector has been in a cyclical downturn for the past couple of years, Farrow said there are some potential bright spots on the horizon for Sudbury.
Glencore is currently undergoing feasibility studies on the Errington and Vermilion mineralization in preparation for a $350-million development that would produce an estimated 2,900 tonnes of ore per day over a seven- to 10-year mine life. The development is expected to create between 200 and 250 jobs.
The Errington deposit was briefly mined in the 1920s following its discovery along the Vermilion River, while the Vermilion deposit was exploited in the 1950s.
The Errington deposit has 5.8 million tonnes of ore, while the Vermilion deposit has 2.5 million tonnes of ore. Although the Vermilion deposit is smaller, it’s considered a richer mineralization.
Both deposits contain zinc, copper, lead and precious metals.
Farrow said a gold deposit near Lake Wanapitei also looks promising, and a rare earth metal deposit near Sturgeon Falls is undergoing an economic viability study.
Despite Sudbury's long mining history, Farrow said its status as a world-class mining jurisdiction will not disappear any time soon.
“So far the mining seems to only be limited by our technology,” he said.