With the release of another batch of assay results from ongoing drilling,
The Roberto mineralized system is now traced over a lateral distance of more than 1.9 km and to a vertical depth of 720 metres, remaining open in all directions. Furthermore, work carried out on the periphery of the Roberto system shows the emergence of new gold-bearing quartz zones.
Roberto, Mid-Roberto and Roberto Est are a series of steeply dipping, sub-parallel mineralized zones hosted in a strongly altered sedimentary package. The zones are part of a replacement-style system of en echelon lenses.
Deep drilling in the central or core area of the main Roberto zone, between section lines 30+00N and 34+00N, continues to show a strengthening of the gold mineralization at depth. So far, Virginia has yet to miss with any of the dozen or so holes that have tested the lower realms of this system below 450 metres vertical depth. (The results from the deep drilling are highlighted in Table 1 below.)
“It just proves that the best part of the system is raking or plunging to the northeast,” says Paul Archer, Virginia’s vice-president of exploration. “I think what we are drilling right now is the plunge of the high-grade intercepts we had at surface. We didn’t get any misses and that is very significant. It just shows how consistent the deposit is, and how big it can become.”
A high-grade section of Roberto, exposed at surface in trenching (section 29+00N), returned impressive channel sample results over a lateral distance of more than 100 metres, including 18.5 grams across 11 metres, 15.5 grams over 10 metres, 12.5 grams across 12 metres, 10.8 grams over 9 metres, 19.3 grams across 8 metres and 16.7 grams over 5 metres.
In the deepest hole to date, ELE-136 intersected a 2-metre interval (equal to a true thickness of 1.7 metres) of 20.5 grams gold per tonne, followed closely by a second 2-metre interval of 28.6 grams, at 930 metres downhole or 720 metres below surface on section 34+00N. This latest hole extended the depth of the mineralization a further 90 metres beyond previously reported hole ELE-126B (section 32+00N), which intersected 23.1 grams across 3 metres (2.4 metres true width), some 200 metres to the south along strike.
Archer is not concerned that the Roberto horizon is narrowing in the latest holes. He says the drilling to date indicates the mineralized horizons do pinch and swell.
Three million oz.
The central area of the main Roberto zone is covered by Ell Lake, which is part of the Opinaca reservoir, so the deeper holes are being drilled by stepping back from the lake’s edge. These holes are over 1,000 metres long, taking about a week to complete.
“The development of a higher-grade mineralized shoot suggests the Roberto zone may locally thicken at depth and/or is influenced by a gentle flexure in the orientation of the mineralized horizon, which indicates a prime exploration target,” wrote Don Poirier of First Associates Investments in a July report. “Surface prospecting and subsidiary zones intersected in the drilling indicate a strong mineral system with multi-million ounce potential.”
He added: “We continue to believe that there is potential for three million ounces of gold within the Roberto zones at the lonore project.”
Canaccord Capital’s Graeme Currie concurs in a recent update: “Our best guess on a rough-approach basis is that the zones may contain between three and three-and-a-half million ounces.”
Virginia, which has yet to make any sort of resource prediction, won’t have an estimate ready until sometime in the first half of 2006, following the completion of the winter drilling program.
Lower Eastmain belt
The wholly owned lonore project is 320 km northeast of the town of Matagami and covers 521 sq. km in the eastern part of the Opinaca Reservoir. The area can be reached by a 60-km-long gravel road off kilometre marker 395 of the James Bay paved road. It is then a 35-km-long journey by barge during the summer months or by snowmobile in the winter. The Nemiscau airport, 100 km due south, provides easy access by helicopter or float plane.
The lonore project is in the Lower Eastmain belt, straddling the contact between two major tectonic stratigraphic assemblages, namely the volcanic rocks of the La Grande sub-province to the south and sedimentary rocks of the Opinaca sub-province to the north. In the vicinity of the Opinaca Reservoir, these rocks are intruded by syn- to late-tectonic diorite and granodiorite plutons. This assemblage of rocks is more than 25 km long and 3-4 km wide.
The 227-sq.-km lonore property block is centred on a diorite-tonalite intrusion measuring 10 km in diameter at the northern margin of a vast batholithic complex and in the contact zone between the La Grande and Opinaca sub-provinces.
lonore is a new, grassroots find. While evaluating the former Ell copper showing in 2002, Virginia discovered a mineralized boulder of altered metasediments in the immediate area, representing a previously unrecognized style of gold-bearing mineralization. A large, 2-metre-diameter, angular boulder of quartzo-feldspathic metasediment, with disseminated arsenopyrite and pyrrhotite, assayed 22.9 grams gold in a grab sample. Re-sampling of the boulder delivered 13.9 grams.
The nature of this boulder and the glacial train of the area suggested that the source area was a few kilometres to the northeast along the contact between the diorite intrusion and a package of sediments lying directly to the north.
While tracking down its source in 2003, many additional boulders of mineralized metasediments were found in an area measuring 4 by 2 km on the northern shore of Ell Lake. Several of these boulders contained anomalous gold, with values as high as 18.6 grams.
Virginia began an extensive stripping program in 2003 and exposed a limited portion of the probable source area — a highly altered and mineralized sedimentary sequence at the margin of the Ell Lake diorite intrusion. The first trenches in the area returned several grabs of better than 1 gram gold, including 29 grams, whereas the results of channel sampling included 37 metres of 0.81 gram, and 5.2 metres of 2.42 grams.
Summer 2004 campaign
The summer 2004 campaign began with further prospecting and hand-stripping in an area where a grab sample taken in the fall of 2003 delivered 10.2 grams gold. This resulted in the discovery of the Roberto showing, which returned 4.29 grams across 12 metres (including 6.16 grams over 5 metres) and 15.8 grams across 3 metres in the first two adjacent trenches.
Using an excavator, Roberto and the nearby Roberto Est zone were exposed at surface over a lateral distance of 250 metres in a north-south direction. Diamond drilling began in September 2004; the grade and the consistent nature of the mineralization hole to hole quickly made obvious the importance of the discovery. To date, Virginia has completed more than 170 holes on the discovery.
The sediments at the northern edge of the intrusion are an assemblage of sandstone-greywacke conglomerate. These sediments are intruded by diorite dykes and appear to be affected by east-west-trending folding and faulting. The sedimentary package grades to pegmatite-bearing paragneisses to the north, suggesting a steep metamorphic gradient. The gold-bearing mineralized horizons are developed in association with some quartz veining and stockwork, and comprised of finely disseminated sulphide mineralization, consisting of 5-8% pyrrhotite, arsenopyrite, pyrite and trace chalcopyrite.
The sediment-hosted gold mineralization is believed to be replacement-type. The gold has an arsenic-antimony signature associated with intense silica-potassic-tourmaline alteration.
“In this model, the underlying diorite intrusion acts as a source of hydrothermal fluid and/or heat source for the hydrothermal system,” s
ays a May 2005 project report. “Some sediment layers have a chemical or competency contrast that acts as a trap for migrating fluids and leads to precipitation of gold.”
Roberto system extended
With three rigs turning round the clock, much of the recent drilling has concentrated on the north shore of Ell Lake, where the Roberto system has been extended an additional 450 metres along strike to the northeast, in spite of some spotty low-grade areas.
“You can’t expect Mother Nature to pour gold on a continuous basis for 2 km and have it spread out equally all the time,” says Archer.
The northern extension is comprised of two main zones, Roberto Est and Zone Biotite (ZB), which are proving to be quite persistent laterally, although at times low in value, admits Archer. Zone Biotite is believed to be the northeast extension of Mid-Roberto: “Basically it’s the same zone,” says Archer. On the northeast extension, Roberto Est and Zone a Biotite have turned from a north-south orientation and are trending in an east-northeast general direction, with a steep dip to the northwest. Based on the surface mapping done this summer, Archer believes the two zones will start to turn back to the northwest, forming some kind of a big anticline to the north.
“What we have defined so far in the Roberto is a basin form, with a plunge to the east,” explains Archer. “But now we will probably define an anticline to the north, and possibly the same thing could happen to the south.”
So far, the strongest results for Roberto Est were obtained at the easternmost limits of the zone on section 68+00E, north of the TR-20 area.
“It’s still wide open,” says Archer.
Here, one of the latest holes, ELR-55, intersected 26.3 grams across 5.5 metres (2.4 metres true width) some 55 metres below surface. Directly overhead, at surface, Roberto Est is exposed in trenching, where channel sampling returned 5.49 grams across 10 metres. Two other nearby holes, drilled in 2004, intersected the Roberto Est zone a further 100 metres to the southwest. Hole ELR-6 cut 1 metre (0.8 metre true width) of 6.45 grams at a vertical depth of 90 metres, and hole ELR-13 intersected 44.7 grams across 2 metres (1.4 metres true width) at 135 metres below surface.
Despite intersecting 7.12 grams across 8.7 metres to a vertical depth of 350 metres in hole ELE-129B (section 62+50E), the latest deep drilling on Roberto Est yielded only 7 metres of 2.05 grams at 380 metres below surface in hole ELR-50 (section 64+00E) and no significant values in hole ELR-57, which tested a vertical depth of 360 metres on section 66+25E.
As for the Zone Biotite, or Mid-Roberto, the zone is proving more discontinuous near the surface.
“We are seeing more and more diorite dykes invading the core of the near-surface Zone Biotite, so accordingly, we see lower values,” explains Archer.
However, he remains encouraged by the results of the deeper drilling, which has encountered: 22.4 grams across 1.5 metres to a vertical depth of 295 metres in hole ELR-57 (section 65+40E); 9.95 grams over 5.3 metres at 375 metres from surface in hole ELR-56 (section 65+00E); and 5.08 grams across 2 metres at a vertical depth of 455 metres in hole ELR-50 (section 63+00E).
“It just shows that sometimes the geology is a little bit more complicated,” says Archer.
The drilling on the northern extension has also identified a network of quartz veins carrying frequent visible gold in the periphery of the two main horizons. Highlights include 1 metre of 71 grams, 1 metre of 28.4 grams, 1.2 metres of 13.1 grams, 1.3 metres of 74 grams, 1 metre of 94 grams, 0.95 metre of 22.3 grams, 1.5 metres of 44 grams and 1 metre of 24.7 grams per tonne. The geometry and true extent of this network of veins is not well defined. Closer-spaced drilling will be required to gain a better understanding of the potential of these mineralized zones
Archer expects to keep the dill rigs turning non-stop until they break for the Christmas holidays, after which (by mid-January) it should be cold enough to begin drilling from the surface of the frozen lake. Virginia is currently contemplating returning to the southeast extension with one of the rigs should the water level of the lake be low enough.
“We are very pleased with the outcome of the exploration program this summer, that’s for sure,” says Archer.
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