Osisko deep drilling gold discovery at Windfall, new wide high-grade Triple 8 Zone
Thursday, Jul 12, 2018
Osisko Mining Inc. is pleased to announce the discovery of a new wide zone of high-grade gold mineralization at depth, at its 100% owned Windfall Lake gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

In May 2018 Osisko commenced two deep exploration drill holes (“Deep Underdog” and “Deep Lynx”) to investigate the potential for depth extensions of the Lynx and Underdog mineralized zones, as well as to further test the intrusion-related geological model for the Windfall deposit. Both holes are still in progress and are advancing towards their primary targets in the outer shell of the porphyry intrusion, at depths of approximately 2500 metres from surface.

The new “Triple 8 Zone”, open in all directions, was discovered in the Deep Underdog hole, DDH OSK-W-18-1603.  Triple 8 is an unanticipated zone of mineralization intersected at approximately 1500 metres downhole, in the planned 2500 metre deep hole. Triple 8 does not correlate with any known zone and is approximately 660 metres east from the closest known mineralized intercept in the Underdog Zone. Maps and sections showing the location of the drill hole and the new mineralized zone are provided on the Corporation’s website. The new discovery zone falls well outside the area of the recently announced mineral resource estimate for the Windfall gold deposit.

Osisko President and CEO John Burzynski commented: “This spectacular new discovery is further proof of concept that the Windfall mineralized system has the potential for world-class grade and scale. This deep hole confirms management’s view that there is significant high-grade gold mineralization at depth, and it underscores what our geological model has been indicating from the beginning: there is a lot of room for Windfall to grow. We are beginning to see increasing intensity in the key alteration and sulfide mineralization as we progress deeper towards what we believe may be the main mineralized centre of the intrusive system. The Triple 8 Zone is over 600 metres distant from any previously known intersection of gold mineralization at Windfall. The original target for this hole is the down-plunge depth extension of the Underdog Zone, which we continue to drill towards a further 750 metres downhole. We believe we have a tiger by the tail.”

The Triple 8 Zone appears to be sub-vertical and was encountered between 1491.3 meters to 1519.6 metres downhole, at a vertical depth of 1025 metres. True thickness is estimated at 20 metres. Mineralization consists of up to 30% disseminated pyrite and pyrite stringers with local visible gold. The mineralization is hosted in altered andesite, with locally pervasive grey silicification and sericitization. Triple 8 is followed by 9 metres (downhole) of chlorite-biotite and garnet alteration, a higher-temperature alteration assemblage than what has been encountered in mineralized zones at Windfall to date.  This appears to be a new style of mineralization at Windfall, as mineralizing fluids followed flow contacts inside the andesite host rather than felsic intrusive contacts (no intrusion is directly associated with this Triple 8 intersection). The zone also contains minor, chalcopyrite, pyrrhotite, arsenopyrite and anomalous molybdenum and zinc values. A number of mineralized sub-zones were also encountered in the hanging wall and the footwall of the new mineralized zone, with assays pending.

OSK-W-18-1603 Mineralization is hosted in a pervasive altered andesite and is subdivided into two distinct intervals. The first interval from 1491.3 metres to 1501.0 metres contains up to 10% disseminated pyrite and stringers, 1% pyrrhotite in nodules, trace chalcopyrite replacing pyrite and local trace arsenopyrite.  In the second interval mineralization is hosted in strong pervasive silica alteration and moderate sericite alteration, containing up to 30% pyrite stringers, up to 8% disseminated pyrite, pyrrhotite patches, trace chalcopyrite and local visible gold occurs within the silica alteration and as fracture filling.

For more information, please visit: https://www.osiskomining.com

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