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Highbank Lake
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Mafic-Ultramafic Intrusions on the Highbank Lake Area
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(click image to enlarge)
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| Northern Shield is exploring its Highbank Lake Property with Impala Platinum Holdings Limited. Impala, the world’s second largest producer of platinum, can earn a 60% interest in the PGE (including PGE by-products) potential of the property by funding $5 million of mineral exploration expenditures within five years. Northern Shield maintains a 100% interest in the chromite rights. The Highbank Lake Property is located in the James Bay Lowlands of north-western Ontario and covers an area of 400 km2 and represents one of the largest untested reef-hosted platinum and chromium prospects in North America. |
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In early 2004, Northern Shield announced the discovery of a previously unknown layered intrusion at Highbank Lake in north-western Ontario, an area of scant outcrop. The layered intrusion extends for over 500 square kilometers, placing it amongst the top ten largest known layered intrusions in the world. Individual layers within the intrusion can be traced from airborne magnetic surveys for distances of 20-40 kilometres. Exploration at Highbank Lake is carried out following a model based on the Bushveld Layered Intrusive Complex in South Africa, which hosts approximately 80% of the world’s known reserves of PGEs in association with chromite-rich layers or “reefs”.
Northern Shield is exploring its Highbank Lake Property with Impala Platinum Holdings Ltd., the world’s second largest producer of platinum, who can earn a 60% interest in the PGE (including PGE by-products) potential of the property by funding $5 million of mineral exploration expenditures within five years from July 2005, the date of the option agreement with Impala. Northern Shield maintains a 100% interest in any chromite or other minerals, which are not extracted as a byproduct of PGE mining. |
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(click image to enlarge)
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| During Northern Shield’s 2005 field season, four boulders of chromitite were recovered from overburden near the center of the property. The boulders, weighing between approximately 2 kg and 28 kg, all contain anomalous platinum, palladium and nickel values, and significant chromium. The discovery of the chromitite is very important as it, together with the abundance of chromite grains and chromitite fragments already recovered from previous stream sediment samples, provides further indication of the likelihood that chromitite layers or “reefs” are hosted within the layered intrusion. The presence of chromitite in the intrusion is critical as PGE mineralization is found within, or proximal to chromite-rich layers in all the major PGE deposits in the world (Merensky Reef and UG2 Reef -Bushveld, J-M Reef -Stillwater and MZS Great Dyke). Chromite is also the source of chromium used in the metallurgical, refractory and chemical industries. The Bushveld Complex in South Africa, contains numerous layers of chromitite, some of which are mined strictly for their chromium ore and one, the UG2, mined for its economic concentration of PGEs. Lithogeochemical analysis of these boulders were compared to analysis reported by Spider Resources Ltd. from chromitite intersected in core at their McFauld’s Lake Project. They revealed very distinct signatures, confirming that the boulders found at Highbank Lake have not been transported from the McFauld’s Lake area.There is currently no operating chromium mine in North America. The Cr2O3 (the naturally occurring compound in which chromium is found) grades of these chromitite samples are amongst the highest discovered in North America. |
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| The first significant drill program to be conducted on the layered intrusion at Highbank Lake was completed in two phases in 2006. A 2000 meter drill program consisting of ten holes was conducted in June and July, with a follow-up 1250 meter program of four holes completed in October and November. Of the fourteen drill holes, twelve intersected the intrusion, one (06HB-02) was abandoned in overburden and another (06HB-08) did not intersect the intrusion. No significant PGE mineralization was identified in either program. However, significant, vanadium (V205) titanium |
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| (TiO2)-iron(Fe) mineralization was encountered in a magnetite reef in hole 06HB-04. The grade and widths are comparable to similar mineralization found in the Bushveld Complex. |
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Despite disappointing results for PGEs, the geochemical trends identified by Northern Shield from the drill cores have been extremely useful in understanding the geometry and orientation of the intrusion. The geochemical pattern observed at Highbank Lake can be compared directly to that of the Bushveld and hence the stratigraphic position of the drill holes within a layered intrusion can be deduced. These comparisons by Northern Shield were supported by Dr. Wolfgang Maier, University of Western Australia, a world reknown expert in the Bushveld and other PGE-bearing mafic-ultramafic complexes.
In March 2007 a small grain of sperrylite (a platinum mineral) was identified in a heavy mineral concentrate from a sediment sample collected by Northern Shield from in an earlier program. The identification occurred during detailed microscope studies of the concentrates by Dr. Richard Taylor of Carleton University in Ottawa. A grain of pentlandite (nickel sulphide) was also identified in another sample taken within 400 meters of where the platinum mineral was found. The location of the samples containing the sperrylite and pentlandite grains coincides with one of the areas suggested by Dr. Maier as being most prospective for PGE mineralization at Highbank Lake.
Since the Company’s acquisition of the property, systematic exploration has provided encouraging results at every exploration phase designed to demonstrate the very high potential for a PGE deposit hosted in a layered intrusion. The interpretation of the current available data suggests that the geological processes that are a pre-requisite for the formation of PGE-bearing reefs according to the model have occurred within the intrusion at Highbank Lake. |
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