The Hushamu (Expo) occurrence is located in the northeastern headwaters of Hepler Creek, approximately 500 metres northwest of Hushamu Lake.
Regionally, the area is underlain by northwest-trending belts of basaltic volcanics of the Upper Triassic Karmutsen Formation and carbonate sedimentary rocks of the Upper Triassic Quatsino Formation (both formations belong to the Vancouver Group) and mafic volcanics and sediments of the Upper Triassic to Lower Jurassic Bonanza Group (Holberg volcanic unit, Nahwitti River wacke and Parson Bay Formation). These volcanic and sedimentary rocks have been intruded by granodioritic rocks of the Early to Middle Jurassic Island Plutonic Suite.
Locally, breccia, tuff, lapilli tuff, and flows (all with an andesitic composition) of the Bonanza Group are intruded by quartz monzonite and dikes of generally dioritic composition. Several areas of intense silicification of the volcanics are thought to represent explosive volcanic centres. These areas show alteration to pyrite, pyrophyllite, clays (kaolinite?) and sericite. They are enveloped by volcanics showing argillic and sericitic alteration. At further distances the rocks show propylitic alteration to chlorite, epidote, clays and minor sericite. Zunyite has been identified by x-ray diffraction methods (A. Panteleyev, personal communication, 1992). These areas are also mineralized with disseminated magnetite with carbonate and laumontite in fractures and joint-controlled veinlets (see Island Copper, MINFILE 092L 158).
The most abundant sulphide is pyrite, which increases in concentration up to 25 per cent near the areas of intense silicification. Chalcopyrite and molybdenite have been found to be associated with one of the centres.
In 1982, diamond drill hole EC-138 yielded 0.308 per cent copper and 0.29 grams per tonne gold over 63.0 metres (Assessment Report 10982).
In 1988, diamond drilling yielded intercepts of 1.1 per cent copper over 3.0 metres in hole E-159; 0.218 per cent copper with 0.23 grams per tonne gold over 23.4 metres in hole E-160; and 0.303 per cent copper with 0.35 grams per tonne gold over 114.8 metres (Assessment Report 19386).
In 1990, a drillhole (EC-171) tested the southern extension of the Hushamu zone yielding approximately 0.374 per cent copper and 0.53 grams per tonne gold over 233.3 metres (Assessment Report 20117).
In 1991, drillhole EC-189 yielded 0.268 per cent copper and 0.11 grams per tonne gold over 78.0 metres (Assessment Report 21759).
In 2008, diamond drilling yielded intercepts of 0.471 grams per tonne gold, 0.423 per cent copper, 0.011 per cent molybdenum with 0.436 grams per tonne rhenium over 179.3 metres in hole HI08-03 and 0.505 grams per tonne gold, 0.303 per cent copper, 0.007 per cent molybdenum with 0.419 grams per tonne rhenium over 164.0 metres in hole HI08-08 (Assessment Report 30714).
In 2014, diamond drilling highlights from the northwest Extension zone included 0.13 per cent copper, 0.02 grams per tonne gold, 0.02 per cent molybdenum and 0.134 grams per tonne rhenium over 96.7 metres in drillhole H14-03 from 107.3 metres down hole, whereas drillhole H14-01C intersected 60 metres grading 0.12 per cent copper, 0.01 grams per tonne gold and 0.002 per cent molybdenum with 0.12 grams per tonne rhenium from 43 metres down hole (Assessment Report 35355). A fifth hole (H14-05) was drilled at the main Hushamu deposit in an area where previous drilling had been widely spaced and returned 135.6 metres grading 0.39 per cent copper, 0.415 grams per tonne gold and 0.009 per cent molybdenum from 24.4 metres down hole to the end of hole at 160 metres depth (Assessment Report 35355).
In 2017, diamond drilling on an area previously determined to be of low-grade mineralization yielded intercepts of 0.19 per cent copper, 0.007 per cent molybdenum with 0.30 grams per tonne gold over 69 metres in hole H-17-02 and 0.10 per cent copper, 0.013 per cent molybdenum with 0.25 grams per tonne gold over 117 metres in hole H-17-03 (Assessment Report 37243).
During 1969 through 1973, BHP-Utah Mines completed programs of soil and rock sampling, geological mapping, and ground geophysical surveys on the area as the Expo claims. In 1974, a program of geological mapping, ground geophysical surveys, and 16 diamond drill holes, totalling 3284.4 metres, was completed. In 1976, a further two diamond drill holes, totalling 236.0 metres, were completed. In 1977, six diamond drill holes, totalling 906.0 metres, were completed on the Expo and Hep claims.
In 1982, BHP-Utah Mines completed a program of four diamond drill holes, totalling 480.0 metres, rock and soil sampling, and a ground induced polarization survey on the area. In 1983, a program of geological mapping and ground geophysical surveys were completed. In 1985, a further six diamond drill holes, totalling 970.2 metres, were completed. In 1988, Moraga Resources Ltd. and BHP-Utah Mines completed a program of geological mapping, rock sampling, and five diamond drill holes, totalling 762.7 metres.
During 1990 through 1992, Moraga Resources Ltd. and BHP-Utah Mines completed programs of rock and soil sampling, geological mapping, and 31 diamond drill holes, totalling 9935.2 metres, on the area. This work extended the known mineralized zone for approximately 200 metres to the south and southeast.
In 1994, Jordex Resources Inc. and BHP Minerals Canada Ltd. completed four diamond drill holes, totalling 972.1 metres, on the area. During this time, Jordex sought partners to provide capital to bring the Hushamu deposit into production. Ultimately, no partner was found, and the mill was decommissioned as scheduled. In the following few years, Jordex continued to examine the potential of the Expo property and flew a 156.1 line-kilometre helicopter-borne geophysical survey on the area. This work identified the geological boundaries along the southwestern and eastern side of the mineralized zone. At this time, proven and probable reserves were reported at 173 237 000 tonnes grading 0.27 per cent copper, 0.34 grams per tonne gold and 0.009 per cent molybdenum (Information Circular 1994-19, page 14).
In 2003, Lumina Copper Corp. purchased Moraga and acquired the core Hushamu claim holdings. At this time, a NI 43-101 compliant measured and indicated resource of 231 000 000 grading 0.28 per cent copper and 0.31 grams per tonne gold was reported (Assessment Report 28375).
In 2005, Lumina carried out property-wide exploration consisting of historic data compilation, a helicopter-borne geophysical survey over the entire property, a relogging exercise, diamond drilling at Hushamu and Northwest Expo, geological mapping, prospecting, and soil sampling. The general conclusion was that the potential for further discovery at the Hushamu deposit was limited. It was noted that the deposit was truncated by faults, rather than continuing below a barren porphyritic intrusion.
In August 2008, IMA Exploration Inc. completed an option agreement to earn up to 70 per cent interest in the Island Copper property. During the fall of 2008, IMA completed a drilling program at northwest Expo and Hushamu. The program consisted of 13 HQ-sized holes, totalling 5123 metres: 11 holes, totalling 4610 metres, were drilled at northwest Expo and two holes, totalling 513 metres, were drilled at Hushamu. The 2008 drilling program at Hushamu was designed to confirm the grade continuity of the core portion of the mineralized zone, particularly for rhenium and molybdenum.
In 2011, Northisle Copper and Gold Inc. completed a program of resampling of historical drill cores, including a re-interpretation of the lithology, structure, and alteration on the Hushamu property. Results from re-assaying correlated well with documented historical abundances of gold, molybdenum, and copper (Assessment Report 32890). Greater than 6000 one-quarter core samples returned an average of 0.391 grams per tonne rhenium, with greater than 600 samples grading 1 gram per tonne rhenium or greater and up to 1.85 grams per tonne rhenium over 438.64 metres, including 11.2 grams per tonne over 3.0 metres in drillhole EC-201 (Assessment Report 32890).
In 2012, Northisle Copper and Gold Inc. announced that the induced polarization survey carried out northwest of the Hushamu deposit had extended the chargeability anomaly associated with the deposit for a distance of 2 kilometres along the projected trend of the deposit. The anomaly, as defined by greater than three times background (greater than 15 mV/V), is at least 800 metres wide and remains open to the southwest on all but one line (Northern Miner, May 23, 2012).
In June 2012, Northisle Copper and Gold Inc. released the initial NI 43-101 resource estimate on its Hushamu copper-gold-molybdenum porphyry deposit (www.northisle.ca). Indicated resources include 304 million tonnes grading 0.21 per cent copper, 0.29 grams per tonne gold, 0.01 per cent molybdenum, and 0.55 part per million rhenium. Inferred resources include 205.6 million tonnes grading 0.18 per cent copper, 0.26 grams per tonne gold, 0.008 per cent molybdenum, and 0.38 parts per million rhenium.
In 2014, five drillholes, totalling 1834.7 metres, were completed at Hushamu. Four of these holes targeted the 2012 induced polarization chargeability anomaly to the northwest to test if the northern part of the deposit might be displaced to the northwest by a series of left-lateral faults occupying the Huchamu Valley. These holes encountered chlorite-magnetite-sericite–altered andesite, silica-clay-pyrite–altered andesite and porphyritic granodiorite. The highest copper grades are associated with chlorite-magnetite-sericite alteration.
In 2015, a block model was prepared constrained by an earlier pit model which encompassed nearly all of the drilling. The final model size was 2500 metres east-west, 2300 metres north-south and 765 metres vertical with a mineral resource, using a 0.15 per cent copper cut-off, of 305.18 million tonnes indicated grading 0.24 per cent copper, 0.28 grams per tonne gold, 0.008 per cent molybdenum and 0.37 grams per tonne rhenium with an additional 188.64 million tonnes inferred grading 0.19 per cent copper, 0.24 grams per tonne gold, 0.007 per cent molybdenum and 0.35 grams per tonne rhenium (Tahija, L. (2017-10-24): NI 43-101 Technical Report - Preliminary Economic Assessment - North Island Copper and Gold Project).
In 2017, North Isle Copper and Gold Inc. completed six diamond drill holes, totalling 1848.0 metres, on the North Island property. Three holes were drilled on the south-central part of the Hushamu deposit, which was previously identified as being low-grade, and yielded appreciable mineralization, indicating that previous drilling had passed along near vertical, post-mineralization breccia dikes.
In 2020, an updated mineral resource for the Hushamu deposit was reported at 472 850 000 tonnes indicated grading 0.20 per cent copper, 0.008 per cent molybdenum, 0.35 grams per tonne rhenium, and 0.23 grams per tonne gold with an additional 414 290 000 tonnes inferred grading 0.15 per cent copper, 0.006 per cent molybdenum, 0.29 grams per tonne rhenium, and 0.18 grams per tonne gold using a 0.10 per cent copper cut-off grade (M3 Engineering & Technology Corp. [2021-03-18]: North Island Copper and Gold Project NI 43-101 Technical Report Preliminary Economic Assessment, British Columbia, Canada).