Otish Mountains, Que. — The buzz of the scintilometer grows louder as consultant Roger Laine springs through the spongy muskeg on his way to a trench carved out of the sediments of northern Quebec’s Otish basin two decades ago.
When he reaches the trench, the buzz becomes a high-pitched whine and the needle on the hand-held instrument designed to measure gamma rays jumps to 1,500 counts per second (cps). It hits home that we are standing on an anomalously radioactive piece of the Canadian Shield.
The trench is one of four that was cut by German uranium explorer Uranerz in the 1980s while hunting for the source of a boulder train that yielded grades of up to 15% U3O8 in the Otish Mountains, about 300 km north of Chibougamau, Que.
Though Uranerz never found the high-grade surface expression of the train, the company drilled about 20 holes with intersections of up to 16 metres grading 0.95% U3O8 before abandoning the project under the pressure of depressed uranium prices.
The Matoush project is now owned by Strateco Resources (RSC-V, SRSIF-O), a Montreal-based junior headed by mining legend Guy Hbert, namesake of the now- closed Bouchard-Hbert polymetallic mine in Quebec. Strateco optioned the property in 2005 as uranium prices were moving north and now has a 100% stake in Matoush, as well as an option to earn a 100% interest in the Eclat property immediately south. The ground south of that is held by Cameco (CCO-T, CCJ-N).
When a group of analysts visited Matoush in mid-September, Strateco was in the midst of a 10,000-metre, 30-hole program to find extensions of a lens of mineralization called AM-15 that was intersected by Uranerz’s program and, more recently, by Strateco’s own drilling campaign.
Promising results
Initial results are encouraging. Hole 10, showcased during the visit, intersected 1.12% U3O8 over 10.5 metres about 25 metres north of AM-15. Although the grades are not as high as those of some comparable deposits in the Athabasca basin of Saskatchewan, they are much higher than the worldwide average.
Most of the visitors seemed reluctant to finger the radioactive core, even with the protection of latex gloves, but the mineralized zone was easy to spot amidst the sediments by its strong association with tourmaline and green chlorite-fuchsite alteration. The zone occurs at a depth of about 250-300 metres within a near-vertical fault that has been traced over a distance of about 7 km.
The same mineralization was observed at a similar depth in hole 18, 100 metres north. Assay results for this hole were still pending at the time of the site visit, but Hbert was encouraged by the lateral continuity of the fault and the considerable distance between the AM-15 lens and this newly found northern expression.
He speculated that the mineralization in hole 18 might represent either a new lens or, better yet, an extension of AM-15. Only further drilling will tell.
The exploration target at Matoush is sediment-hosted deposits related to unconformities, similar to those found in the Athabasca basin, the epicentre of global uranium exploration and production. The combination of faulting and coarse-grained host rocks at Matoush yields the ideal porosity for this type of mineral deposition from uranium-bearing fluids.
The host rock is an active channel facies (ACF), or a layer of pebbles, that occurs at surface, at the current target depth of 250 metres and again at 350 metres. Although Strateco is focusing on known mineralization in the middle layer in order to calculate a National Instrument 43-101-compliant resource as soon as possible, prospecting is ongoing to find the surface expression of the high-grade boulder trains.
The deeper ACF layer has been tested by hole 17. Although assay results are pending, the hole showed typical alteration associated with a shear zone from 469-477 metres, but weak mineralization with gamma readings of only 200 cps. Strateco expects the results from this and other holes within weeks.
Meanwhile, drilling along the Matoush structure continues at 100-metre spacings to identify new mineralized lenses within the middle ACF facies. To date, the structure has been traced over a strike length of more than 160 metres and a vertical height of 60 metres, but could be as long as 7 km.
The company is currently operating a single drill, but will mobilize at least one more as soon as the winter road that passes within 7 km of the property on its way to the old Eastmain gold mine becomes accessible.
“There’s a good reason we want another drill,” says Hbert. “We want to reach 700 to 800 metres to test the basement-sediment contact.”
Just as explorers in the Athabasca basin are finding evidence of high-grade uranium mineralization not only in the sediments above the unconformity, but in the basement rocks below, Hbert believes there is a good chance of striking mineralization in the basement rocks at Matoush.
Geophysics is also a useful tool for finding uranium deposits. During the summer, Strateco flew a radiometry, magnetometry and electromagnetic survey over the 166.2-sq.-km Matoush property. The survey detected three anomalous areas that have become high- priority exploration targets for the company.
“We need to do more ground geophysics to try to trace the fault (that hosts the uranium mineralization) with the best detail we can get,” says Jonathan Lafontaine, Strateco’s project geologist. “We are seeing sniffs of more lenses here and there.”
For instance, Strateco installed 120 radon detectors along a 2-km section of the Matoush structure to test their ability to detect the structure, trace its extensions and find new zones of potential mineralization. The results indicated anomalies near the Uranerz trenches and other weaker anomalies in less well-known areas.
Poor recovery
One of the main challenges at Matoush is ore recovery. Much of the mineralized core from the first few holes drilled on the property were lost and hole 18, the 100-metre stepout hole viewed by analysts on-site, also showed signs of poor recovery within the mineralized zone.
Though down-the-hole gamma ray probes can be used to provide grade estimates, this method is not consistently reliable and core recovery at Matoush will continue to be a challenge for the drillers.
Strateco is well financed to complete the current phase of drilling and launch the next. Earlier this year, the company completed a $9-million financing of 7.2 million shares at $1.25 apiece. The shares currently trade in the 80-85 range.
If Matoush continues to yield encouraging results, established and near-term uranium producers hungry for more resources are likely to come circling. Hbert has a reputation among mining circles for nurturing exploration projects to the buy-out phase.
Perhaps his finest hour was Cambior’s purchase of Audrey Resources in the 1990s after the junior developed the Bouchard-Hbert mine near Rouyn-Noranda under Hbert’s leadership. Let’s see if he can do it again.
— The author is a freelance writer specializing in mining issues, and principal of Toronto-based GeoPen Communications (www.geopen.com).
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