The Vanguard Extension showing is located 0.5 kilometre northwest of the West Kitsault River, 28.0 kilometres north-northwest of Alice Arm. A zone of copper mineralization was explored by tunnelling between 1928 and 1931.

The showing occurs at the western margin of a 10.0 kilometre long, northwest trending body of gossanous plagioclase-hornblende porphyritic andesite of the Lower Jurassic Hazelton Group. The andesite, informally called the "Copper Belt", has been extensively pyritized and is variably silicified and sericitized along its length.

The showing consists of an undefined zone of pyrite and chalcopyrite in silicified andesite. Tunnelling failed to define the size and attitude of this zone.

In 1927, the Vic Spencer group optioned the Vanguard ground and drove the long lower tunnel on the main copper showing, but dropped the option the same year after a disagreement with the owner. To the present time (ca. 1966) about 274 metres of underground work has been completed, as well as a number of short trenches and opencuts; no ore has been shipped from the Vanguard. In 1966, Canex Aerial Exploration Ltd. conducted surface and underground geological mapping, a geochemical survey and an electromagnetic survey. During 2017 through 2019, Auryn Resources Inc. completed programs of geological mapping, geochemical (rock and soil) sampling, airborne and ground geophysical surveys and re-logging of historical drill cores.