The North Fork occurrence is located on the south side of Kate Ryan Creek, 8 kilometres southeast of Stewart. Several small shipments of high-grade ore were made from this location between 1919 and 1924.
The occurrence is comprised of two veins which are developed in north to northwest striking, steeply west dipping argillite of the Lower Jurassic Unuk River Formation (Hazelton Group). The first vein, situated in a shear zone, is 1 metre wide, strikes north and dips 45 degrees west. The second vein is 0.3 metre wide, strikes west, dips 60 degrees north and is offset by a fault. Mineralization consists of pyrite, galena, sphalerite and tetrahedrite in a gangue of quartz.
Two shipments of sorted ore from the first vein totalling 9 tonnes averaged 3872 grams per tonne silver, 14.4 per cent lead and 4.4 per cent zinc (Minister of Mines Annual Report 1919, pages 63, 64 and 1924, page 59).
In 1919, work consisted of shaft sunk 12.8 metres following the vein part way, but bearing off into the footwall, necessitating a crosscut of 5.2 metres from the bottom of the shaft to pick up the vein again. The wall of the vein was traced from the shaft down the hill and a tunnel driven on it to a point underneath, and about 9.1 metres lower than the bottom of the shaft, without locating the vein. On the supposition that the tunnel followed the same slip that carried the shaft into the footwall, it would take a crosscut of about 8.8 metres from the tunnel to get over to the vein. In 1926, an option was taken on the property by W. Harner, who put up a temporary camp and drove a crosscut a distance of 28 metres to the right, intersecting 9.1 metres of vein matter but not to the hangingwall, the work having to be stopped on account of the coming of snow. In 1980, work by Deleen and Klepacki consisted of geological mapping and sampling on the Fraser group of claims (103P 097). In 1988, an airborne VLF-EM and magnetic survey was flown by Hermary and Woods on the Heat 1-3 claims. In 1989, the Rainbow 1-3 claims were staked by J. Foerester which covered the Fraser showing and North Fork showing. In 1990, Golden Arrow Resources Inc. collected a total of 13 rock samples and 36 sieved stream sediment samples for analyses. In 1991, Golden Ring Resources Ltd. conducted an exploration program on the Rainbow 1-3 claims which consisted of prospecting, detailed geological mapping, rock and soil sampling, trenching, and reconnaissance VLF-EM surveying. Most of the work was concentrated on the Fraser showings (103P 097) with reconnaissance of the Lower Tunnel (Crawford) and North Fork Basin areas. In 2009, Castle Resources Inc. entered into an option agreement with the registered claim holders of the Horseshoe property claims, J. Wang and R. Kasum, and a one day prospecting and sampling program was conducted.
Granby Gold Inc.'s Marmot property, containing the North Fork prospect, had its geology refined in 2017 by interpretation with regional airborne geophysics and again in 2018 with airborne geophysical survey data. There is apparently no strong geophysical expression of the North Fork occurrence (Assessment Report 38124).
