The Dorothy occurrence is located 5 kilometres east of the south end of Nakinilerak Lake, approximately 20 kilometres northeast of the Bell mine (093M 001) and about 80 kilometres northeast of the community of Smithers. The property was staked originally in 1965 and has been confused with Amoco's Haut and BI claim groups to the southeast. The prospect lies adjacent to, or in the southwestern corner of the Kam 1-56 mineral claims, Hautete Creek Group, Babine Lake Project of Kerr Addison Mines Limited. Reserves were outlined in 1976.

A biotite feldspar porphyry circular plug or dike, 1300 metres in diameter, of the Eocene Babine Intrusions (Babine Plutonic Suite) is cut by north- and east-striking fractures. The porphyry occurs at the contact between dioritic rocks and volcanic rocks. The main rock types in the area are andesitic tuff, possibly of the Jurassic Hazelton Group, and Late Cretaceous(?) dioritic intrusive rocks.

The fractures contain quartz and disseminations and stringers of pyrite, some chalcopyrite and minor bornite, covellite, pyrrhotite, molybdenite, sphalerite and galena. Potash feldspar rims some of the veins. The deposit is elliptical in shape and is 540 by 300 metres in size. Drilling outlined a large area with copper grades slightly greater than 0.2 per cent with no significant higher-grade core as in the Morrison deposit (093M 007). The copper zone is surrounded by an annular pyrite halo.

Historic inferred reserves to 160 metres are 40,819,500 tonnes grading 0.25 per cent copper and 0.01 per cent molybdenum (Canadian Institute of Mining Special Volume 15 (1976), Table 1, No.93).

Work History

The Kam 1-56 claims, also known as the Hautete Creek Group, were staked by Kerr Addison Mines Limited in 1965. These were located immediately north of the Dorothy area. Over the next year, magnetic and electromagnetic, self-potential and geochemical surveys were completed. This work identified two anomalous areas, known as the A and B anomalies. An unknown amount of diamond drilling was performed by Kerr Addison Mines in 1967.

The Haut and Hi groups, totalling 46 claims, were held in 1965 and 1966 by Noranda Exploration Company, Limited. Geochemical and geophysical surveys were carried out at that time.

Weak copper and molybdenum-in-silt anomalies drew workers to the area during the 1960s. Prospecting revealed what was believed to be an unaltered intrusion, not resembling the distinctive biotite feldspar porphyry (BFP) known to host many porphyry copper deposits in the region and as a result, claims were not acquired. Subsequent thin section work, however, indicated the intrusion is likely a trachytic variety of the BFP which has been subjected to two periods of alteration.

The original Dorothy claims were staked in 1969 for Evergreen Explorations and were subsequently vended to Twin Peak Mines Limited. Ducanex Resources Limited formed a joint venture partnership with Twin Peaks whereby Ducanex held 90 per cent and Twin Peaks 10 per cent of the Dorothy property. International Corona has retained Ducanex’s 90 per cent interest in the property.

The 1970 field program entailed an induced polarization survey, soil sampling, magnetometer and Very Low Frequency Electromagnetic surveys, and geological mapping. The induced polarization survey outlined a large area (1000 by 1300 metres) of coincidental chargeability high and resistivity low. This anomaly extended off the grid, both to the north and the south. Trenching was completed using a bulldozer to uncover what was described as local zones of ore grade porphyry copper-molybdenum mineralization in a 0.2 per cent copper background.

Between October 1970 and September 1971, 2973 metres of drilling were completed in 29 holes. Drilling intercepted consistently anomalous but low-grade copper mineralization (weighted average over the 20 best mineralized holes gives 0.2 per cent copper and 0.019 per cent molybdenite). The property lay essentially dormant until 1991.

Prospecting of the Dot and Sin claims occurred in 1995 by owner L. Hewitt who followed in 1996 by collecting a total of 127 soils, 65 rock, and 1 stream sediment. The Dot and Sin claim surrounded the original Dorothy tenures but did not include them.

In 1995, Teck Corporation conducted a large airborne magnetic and scintillometer survey totaling 4200 line-kilometres that covered many prospects in the region including the Dorothy.

In 2007, Copper Ridge Exploration Inc. held the Nak (093M 010) tenure, located 6.1 kilometres north-northwest, and contiguous tenures to the south that included the Dorothy prospect. A total of 14 kilometres of induced polarization surveying and 13.7 kilometres of magnetometer surveying was done, but the survey was terminated before completion on the Dorothy due to severe winter conditions.

In 2008, the Copper Ridge Explorations Inc. exploration program included prospecting, soil sampling (consisting of 735 samples) a 54.54 line-kilometre induced polarization survey (started late in 2007) and a magnetometer survey. The soil survey extended from north of the Nak prospect to south of the Dorothy prospect. The induced polarization survey covered the Nak and the Dorothy prospects. This was followed up by drilling five holes totaling 1265 metres. One hole was drilled on the Dorothy to test a soil anomaly and coincident chargeability high while the remaining four holes were drilled on the Nak to test the eastern extension of the Southern zone and a possible southwestern extension of this zone. The Dorothy hole intersected predominantly disseminated pyrite with minor chalcopyrite and appeared to be drilled within the pyrite halo of the deposit. At the Nak, the Southern zone drillhole was mineralized from the collar to the end (316.5 metres) and assayed 0.115 per cent copper and 0.257 gram per tonne gold with significant higher-grade intervals (Assessment Report 32356). The other holes intersected mainly pyrite and narrow zones of low copper.

Historical drilling (including 2008 drilling) is reported to consist of 107 core holes, 29 on the Dorothy occurrence on the southern part of the Babine property and 98 on the Nak occurrence on the northern part of the property.

In 2009, a two-day till sampling program resulted in the collection of 11 samples. The 2010 work program of Copper Ridge Explorations Inc. consisted of the collection of 460 soil samples over the Nak deposit. A helicopter ZTEM survey was flown totalling 506 line-kilometres. The most significant result of the soil survey was three coincident copper-molybdenum-bismuth anomalies at the Nak prospect. The ZTEM survey was reported to have corroborated the results of previous ground surveys and provided continuous magnetic and electromagnetic coverage of the entire property.

In December 2016, Amarc Resources Ltd. acquired the Duke property which now covers the Dorothy occurrence. In May 2017, a high resolution heli-borne magnetic survey was completed over parts of the Duke by Amarc Resources. The survey consisted of 392 line-kilometres and outlined major northeast and northwest trending structures and associated cross-structures along with inferred batholithic intrusions. Exploration diamond drilling work was carried out in October and November 2017; two NQ drillholes totalling 1045.5 metres were completed to test the continuity of mineralization of the Dorothy deposit at depth and laterally. This work confirmed significant copper-molybdenum-silver-gold mineralization to a vertical depth of at least 440 metres below surface, which is 330 vertically metres below the limits of historical drilling. Significant intersections from the 2017 drill program include: 120 metres grading 0.32 per cent copper, 0.015 per cent molybdenum, 1.1 grams per tonne silver and 0.05 gram per tonne gold in drillhole DK17001; and 113 metres grading 0.25 per cent copper, 0.014 per cent molybdenum, 1.4 grams per tonne silver and 0.08 gram per tonne gold in drillhole DK17002 (Assessment Report 37293).

In May 2017, B. Kreft of Whitehorse, Yukon Territory contracted R. Beck Consulting Services of Smithers to conduct a field exploration program on the Nak property claims. The program comprised soil and biogeochemical sampling over specified gridded areas within the middle of the claim group. The sampling was designed to provide additional data layers to an area identified by geophysical surveys as having mineral potential.

In 2018, Amarc Resources Ltd. completed six diamond-drill holes totalling 3061.6 metres in an effort to expand the known mineralization and test continuity of mineralization, both at depth and laterally. This drilling expanded the understanding of the deep mineralization to the east, northwest, and southwest of the 2017 drillholes. Drilling on the main zone yielded up to 0.24 per cent copper, 0.012 per cent molybdenum, 1.1 grams per tonne silver and 0.052 gram per tonne gold over 318.00 metres (98.00 to 416.00 metres down hole) in hole DK18006, whereas a step out drillhole (DK18004), collared 1 kilometre north of the other drillholes on the main zone to investigate a possible dextral offset of the mineralized zone, yielded 0.22 per cent copper, 0.01 per cent molybdenum and 1 gram per tonne silver over 93 metres (88.00 to 181.00 metres down hole; Rebagliati, C.M., Titley, E. [2020-04-29]: Technical Report Summarizing Exploration Work on the DUKE Project, Babine Porphyry Copper District, Central British Columbia, Canada [Revision 1]).