The Portland showing is located about 3.2 kilometres northeast of the confluence of American Creek and the Bear River, approximately 21 kilometres northeast of Stewart.

The area is underlain by Jurassic Hazelton Group rocks. The Lower Jurassic Unuk River Formation lies on the west limb of the north trending Bromley syncline (Bulletin 63) and is unconformably overlain to the east of the showing by the Middle Jurassic Salmon River Formation. North trending diorite dikes are conspicuous in the area (Bulletin 58).

The showing comprises a narrow, north striking, steeply west dipping quartz vein, up to 0.6 metre wide, in a zone of brecciated argillite. The vein is exposed in a 60 metre long tunnel. Pyrite is reported to be the principal sulphide present. A grab sample assayed 8.6 grams per tonne gold and 432 grams per tonne silver (Geological Survey of Canada Memoir 175).

On the Ibex 6 claim, a 6 metre wide shear zone showing quartzose replacement, contains disseminated chalcopyrite, galena and sphalerite. A sample across 4.3 metres assayed only traces of gold and silver (Minister of Mines Annual Report 1931).

In 1910, the Portland Bear River Mining Co. Ltd. acquired the Ruby Fr. 1, Ruby Fr. 2, Signal, Sicker, Eureka, Harrold, Snowslide and Rock Creek claims. During 1910-12, the company carried out tunnelling and opencutting. In 1925(?), S. Deschamps acquired the Portland 1-3, 4 Fr., 5-6 and Ibex 1-2 claims covering the showing. In 1931, prospecting and further opencutting were reported on the Ibex 6 claim.

During 2005 through 2010, Auramex completed programs of prospecting, geological mapping, geochemical sampling and airborne geophysical surveys on the area as the Bear River-Surprise Creek property.