This occurrence is on the west bank of Siwash Creek, 1.6 kilometres north-northwest of the creek's confluence with Tepee Creek, 38 kilometres northeast of Princeton.
This prospect is hosted in a stock of quartz porphyritic monzonite/granite, near its southwestern margin. The stock intrudes granite of the Middle Jurassic Osprey Lake batholith. This stock is one of a series of small granitic bodies of early Tertiary age referred to as the Otter intrusions. The granite exhibits strong kaolinite-sericite-silica-carbonate alteration.
The Snowstorm deposit is comprised of two prominent shear zones/breccia veins, and several smaller shears in the vicinity. The two main shears strike 035 and 065 degrees and dip steeply northwest and 45 degrees southeast respectively. The zones are 0.15 to 1.8 metres wide respectively. They are mineralized with abundant pyrite, and some sphalerite and galena, as blebs and small grains, in a gangue of quartz and brecciated wallrock. A chip sample from the bottom of the No. 1 adit assayed 15 grams per tonne gold, 699 grams per tonne silver, 5 per cent lead and 16 per cent zinc across 0.6 metre (Minister of Mines Annual Report 1929, page 278). A chip sample across a vein cut in the No. 2 tunnel assayed trace gold, 55 grams per tonne silver, 1 per cent copper and 13.4 per cent zinc over 0.15 metres (Minister of Mines Annual Report 1929, page 277).
Similar copper, lead and zinc mineralization occurs in quartz veins and siliceous zones east and west of the two shears on both sides of Siwash Creek. One area referred to as the Monty showing, is situated on the east side of the creek, about 140 metres east-southeast of the underground workings. A sample of sphalerite mineralization analysed 0.090 gram per tonne gold, 8.6 grams per tonne silver, 0.0590 per cent copper, greater than 1 per cent zinc and 0.0244 per cent lead (Assessment Report 18211, rock geochemistry map, sample 31). A hole drilled on the west side of the creek, 230 metres south-southwest of the two adits, intersected quartz stringers mineralized with pyrite, sphalerite and galena. A section of this mineralization yielded 15.6 grams per tonne silver, 0.572 per cent lead and 1.209 per cent zinc over 7.7 metres (Assessment Report 19472, page 18, hole SS-81-24, 33.5 to 41.2 metres, samples 24659 to 24663).
Work History
The occurrence was initially developed by local prospectors between 1925 and 1928. This work included the development of three adits (Three Adit Gap zone) comprising approximately 120 to 150 meters of drifting in total with 9 to 15 meters of development on the No. 1 adit, located on the east bank of Siwash creek, 91 meters of development on the No. 2 adit, located on the west bank of Siwash Creek across from the No. 1 adit and 38 meters of development on the No. 3 adit, located 18 meters south of the No. 2 adit. Two other adits, referred to as the Monty (Chicago zone) and Claremont adits, were developed on the east bank of Siwash Creek, approximately 150 and 250 metres downstream (south) of the Three Adit Gap adits.
Siwash Development Company Ltd. continued underground development in 1951 and 1952. The company drifted on one of the mineralized shears, but no ore was shipped.
Brenda Mines Ltd. conducted Induced Polarization (I.P.) geophysical surveys, soil geochemistry surveys, and drilled 26 diamond drill holes in during 1979 through 1981. Westron Venture Ltd. drilled up to 12 rotary drill holes on or in the vicinity of the occurrence in 1987. In 1988, International Tower Hill Mines Ltd. acquired the property and completed a program of soil sampling and minor rock sampling. In 1989, Inel Resources re-logged and sampled for gold the previous 26 drill holes performed by Brenda Mines along with a program of geological mapping and limited rock and soil sampling.
During 1991 through 1993, International Tower Hill Mines completed programs of soil sampling and the adits at Three Adit Gap and Fissure Maiden occurrences were rehabilitated and re-sampled. In 1994, a further program of soil sampling, prospecting, geological mapping, geophysical surveys and 33 percussion drill holes were completed. Drilling yielded values of up to 0.12 gram per tonne gold, 15.4 grams per tonne silver and greater than 1.00 per cent lead and zinc, respectively, over 1.5 metres intercepts in holes 94-14 and 94-15 (Besserer, D.J. (2007-05-27): Technical report on the precious and base metal potential of the Siwash Creek Property).
In 1995, six percussion drill holes, totalling 378 metres, were completed. In 1996 and 1997, a further ten drill holes, totalling 1637 metres, were completed. In 2001, six drill holes, totalling 1055 metres, were completed. In 2004, five diamond drill holes, totalling 1013 metres, were completed.
In 2006, Ravencrest Resources Inc. completed a program of prospecting and geochemical (rock, stream sediment and soil) sampling on the area as the Siwash Creek property. A sample (06KRP421) of quartz vein material, taken 6 metres above the No. 2 adit assayed 0.45 gram per tonne gold, 454 grams per tonne silver and 0.39 per cent lead. Also at this time, a chip sample (06RTP226) of quartz eye porphyry from the Monty zone yielded 16.67 grams per tonne silver, 4.41 per cent zinc and 0.18 per cent lead over 2.0 metres, while a sample (06KRP420) from a mineralized banded quartz vein from the Claremont adit yielded 2.86 grams per tonne gold, 46.8 grams per tonne silver, 2.13 per cent zinc and 2.18 per cent lead (Besserer, D.J. (2007-05-27): Technical report on the precious and base metal potential of the Siwash Creek Property).
In 2010, Ravencrest and River Wild Exploration Inc. completed a 496 line-kilometre airborne electromagnetic (VTEM) survey on the Siwash property. This work identified two combined conductive high-magnetic low anomalies. In 2011, a minor rock sampling program was conducted on the property. A grab sample (11KRP103) from the Monty West trenches assayed 60.5 grams per tonne silver, 0.98 per cent lead and 0.27 per cent zinc (Moroney, D.M. (2012-06-04): Technical Report on the Siwash Creek and River Wild Properties).
