The Portland occurrence is located approximately 1.95 kilometres west-northwest of the north end of Bluey Lake and 2.6 kilometres southwest of the south end of Kentucky Lake.
Regionally, the area is underlain by the Upper Triassic Nicola Group, which regionally consists of alkalic and calc-alkalic volcanics and intrusions of island arc origin, and which is the principal component of the Quesnel terrane in southern British Columbia (Geological Survey of Canada Maps 41-1989, 1713A). The area lies in the Central Belt or facies of the Nicola Group (after Preto, Bulletin 69). This belt of rocks mainly consists of subaerial and submarine, red or purple to green augite plagioclase porphyritic andesitic and basaltic flows, volcanic breccia and tuff, and minor argillites and limestone. The volcanics are intruded by bodies of comagmatic Upper Triassic to Lower Jurassic diorite to monzonite. The area is characterized by long-lived, primarily north-striking faults and related fracturing, which originally controlled intrusion emplacement. East-striking faults are subordinate, and commonly offset intrusive contacts.
Locally, chalcocite, magnetite and hematite occur in a fracture zone in red and green laharic breccia of the Upper Triassic Nicola Group (Central Belt, Bulletin 69). The mineralized zone is reported to be greater than 9 metres wide.
In 1901, a sample from an opencut assayed 0.9 per cent copper (Minister of Mines Annual Report 1901, page 1183).
In 1913, a sample from approximately 100 tonnes of dump material assayed 0.4 per cent copper (Minister of Mines Annual Report 1913, page 223).
In 1996, a composite grab sample (28501) of andesite to basalt with quartz±carbonate stringers and malachite yielded 1.52 per cent copper and 6.8 grams per tonne silver, whereas a nearby chip sample (28502) yielded 0.34 per cent copper over 4.5 metres (Assessment Report 24522). Also at this time, a composite sample (28506) of dump material adjacent to the Portland shaft yielded 0.75 per cent copper, whereas a composite grab sample (28509) of silicified and malachite-stained andesite to basalt, taken northwest of the previous samples, yielded 0.97 per cent copper (Assessment Report 24522).
In 1997, two grab samples (28345 and 38246) of carbonate-, chlorite- and hematite-altered andesitic volcanics hosting malachite yielded 0.166 and 0.362 per cent copper, respectively, whereas four composite grab samples (28347 through 28350) of waste and ore dump material from the Portland shaft yielded from 0.311 to 1.125 per cent copper with 1.6 to 5.0 grams per tonne silver (Assessment Report 25158).
In 2006, a shaft dump sample (K-06) yielded 0.170 per cent copper (Assessment Report 28782).
Work History
The occurrence was explored periodically between 1900 and 1905. In 1905, Portland Mining Company excavated a 35-metre-deep shaft, and a 32-metre-long drift from the bottom of the shaft.
In 1956, Fidelity Uranium Mines Ltd. completed a program of geological mapping and trenching on the area immediately southeast of the occurrence as the Nor claims.
During 1975 through 1981, Fred Gingell completed programs of geological mapping, geochemical (soil and rock) sampling and geophysical surveys on the area immediately east of the occurrence as the Bluey claims.
In 1990, MineQuest Exploration Associates Ltd. completed a minor program of prospecting, geological mapping and rock sampling on the area as the Al 1-3 and Ken claims. In 1992, Pacific Copper Fields Inc. and MineQuest Exploration Associates Ltd. completed a program of geological mapping and rock sampling on the claims. In 1996 and 1997, Len Harris and later Matrix Energy Inc. completed programs of prospecting and rock sampling on the area as the Tom Cat and Climax claims.
In 2006, Bold Ventures Inc. completed a program of geochemical (rock and soil) sampling and a 28.0-line-kilometre induced polarization survey on the area as the Casper claims of the Kentucky Lake property.
In 2013, Victory Resources Corp. completed a photogeological structural (lineament) analysis on the area. In 2018, Enduro Metals Corp. completed a minor program of prospecting, geological mapping and sampling on the area as the Tom Cat property.
