The Kalzas W-Sn-Mo deposit is located in central Yukon, 282 km north of Whitehorse on the northern side of Big Kalzas Lake. Wolframite-molybdenite-cassiterite mineralization occurs in sets of large planar quartz veins which cross-cut Selwyn Basin clastic rocks of the Upper proterozoic Windermere Supergroup, or "Grit" unit. The deposit has a concentric alteration halo with an outer sericite dominated zone, an inner "potassic' core and intense tourmalinization throughout the potassic zone and part of the sericite fringe. Intense fracture and quartz-tourmaline veinlet stockwords are present. No plutonic rocks are exposed in the local area though an underlying pluton is suspected.
Kalzas has similarities to many wolframite deposits throughout the world, including those of southeast Asia which contain the bulk of world tungsten reserves. In contrast, North American tungsten mines having wolframite as the dominant tungsten phase are not as common as scheelite skarn deposits which produce most of our domestic tungsten.