The Santa Rosa showing is underlain by Lower Jurassic Elise Formation rocks of the Rossland Group comprised of andesite, tuff, agglomerate, breccia and black siltstone. The Rossland Group rocks are intruded by the Middle Eocene Coryell Intrusions comprised of syenite to monzonite stocks. Mineralization consists of shear- controlled sulphide-bearing vein structures ranging up to 3 metres in width. The dominant orientation is 150 degrees with a secondary set at 025 degrees. Both have steep to moderate dips. The veins appear to be associated with contacts of the syenitic intrusives.
At one location a 1-metre wide quartz-clay-lithic breccia sulphide vein is exposed in a trench. It is hosted in a shear trending 168 degrees and dipping 72 degrees north within silicified, variably gossanous andesite. Pyrite, chalcopyrite, galena and sphalerite occur in stringers parallel to the veins margins, as well as isolated blebs and disseminations. A 0.5-metre chip sample (SRR-030) assayed 1.59 grams per tonne gold, 4.9 grams per tonne silver, 0.34 per cent copper, 0.33 per cent lead and 0.14 per cent zinc (Property File - Uptown Industries Corp., Prospectus, May 9, 1989, page 14).
Similar mineralization to the previous sample is exposed along five metres in andesite outcrop located about 700 metres to the northwest. An exposure of quartz-feldspar porphyry is found 10 metres south of this area. A 1-metre chip sample (SRR-036) of the porphyry assayed 0.122 per cent tungsten (Property File - Uptown Industries Corp., Prospectus, May 9, 1989, page 14). About 1.5 kilometres to the northwest on Santa Rosa Creek, about 200 metres upstream from the Swehaw Creek confluence, is another tungsten showing. A zone of pyritized and silicified pods occur, up to 10 cubic centimetres in volume. These zones are hosted by andesite that is cut by granitoid dykes. A grab sample (SRR-101) assayed 0.178 per cent tungsten (Property File - Uptown Industries Corp., Prospectus, May 9, 1989, page 15).
In 1943, Cominco was reported to have prospected a tungsten property located west of Big Sheep Creek about 1.5 kilometres south of the Cascade highway (Minister of Mines Annual Report 1943, page 79). Twenty three metres of trenching was done near an igneous contact that apparently hosted minor disseminated scheelite.
In 2006, Major Gold Limited conducted a mineral exploration program on the Portland Project. This included prospecting, grid surveys, soil geochemistry, rock sampling, and magnetometer surveys. Results from the soil grid geochemistry survey and the magnetometer survey showed anomalous gold, silver, copper, arsenic, lead, and zinc patterns correlating to known mineralization on the property.
