Exploration History

Apparently first discovered in 1892 by prospectors from the Cassiar Gold Fields and rediscovered by K. McMillan, who staked it as the Dorothy cl (15509) in Aug/30 and restaked as South Nahanni cl 1-50 (57465) and Dorothy cl (57470) in Oct/48. Noranda Exploration Company Ltd purchased the property in late 1948 and optioned it in 1949-50 to New Jersey Zinc Exploration Company Ltd, which hand trenched and drilled 4 holes (200 m).

The earliest fringe staking was Kic & Ski cl (60073) in July/50 on the north side of Noranda Lake by F.J. Schtiick & J. Urbanowski, who hand trenched in 1951. Prospectors Airways Company Ltd tied on the HR cl (68620) to the south in May/54 on behalf of a syndicate including Noranda and Kerr Addison Mines Ltd. The property was extensively fringe staked in Dec/65 as Red, Fort, etc cl (89489) by Redfort Prospecting Syndicate (Redstone Mines Ltd, Rayrock Mines Ltd, Elgin Petroleum Corporation Ltd and Fort Reliance Minerals Ltd), which conducted an airborne mag and EM survey in 1966 and 1967. During 1968, Fort Reliance Minerals Ltd acquired the interests of its partners and drilled 6 holes (583 m) on geophysical anomalies.

In 1951 Asarco Exploration Company of Canada Ltd joined the Noranda-New Jersey Zinc joint venture and a new company was formed, Liard River Mining Company Ltd. Both Asarco and Noranda later acted as operator at different times. Exploration consisted of 93 holes (7058 m) between 1951 and 1973, an IP survey in 1967, a geochem survey in 1970-72, a legal survey in 1972 which led to several claims being leased in 1973, the addition of QTZ and Strat cl (Y84112), a gravity survey and 27 holes (about 2530 m) in 1975, linecutting, soil sampling and CEM, VLF and gravity surveys on the new claims, plus 27 holes (2530 m) on the old claim block in 1976, 2 holes (265 m) on the east side of the main zone in 1977, 25 holes (1981 m) in 1980 and 6 holes (640 m), geological mapping, gravity and EM surveys in 1981 on the southeast side.

In 1990, Noranda conducted a two-phase program of soil sampling, followed by bulldozer trenching of anomalous areas (7 trenches - 810 m).

American Smelting and Refining Company and Liard River Mining Co Ltd conducted a reclamation program on the M 19 and South Nahanni 1 and 11 claims in Sept/93. In the succeeding years Liard River has allowed most of their claims to lapse. As of May/2002 the property consists of 18 claims which cover the actual deposit.

Capsule Geology

The McMillan zinc-lead-silver deposit contains 1.1 million tonnes grading 8.3% zinc, 4.1% lead and 62 g/t silver in a tabular, manto-like body near the top of the Neoproterozoic-lower Cambrian undivided Vampire and Narchilla formations. The Main Zone is 600 x 150 m in plan, 2 to 30 m thick, and dips gently east. A second deposit (the South Zone) occurring 300 m to the south contains reserves of 0.4 million tonnes grading 9.3% lead, 1.7% zinc and 214 g/t silver. These figures are not National Instrument 43-101 compliant thus they must be considered historical mineral resource estimates. The property is covered by extensive glacial drift up to 50 m thick, and only the edge of the deposit is exposed along Mine Creek.

Both concordant and discordant styles of mineralization are known. Massive sulphide mineralization at the discovery outcrop is clearly discordant and occurs along the sole of a low-angle fault which separates an upper package of quartzite and massive grey limestone from bleached, silicified and clay-altered phyllite. This fault, termed the 'Black Fault' by Noranda geologists, forms the base of the mineralized horizon in most of the drillholes. Discordant mineralization consists of galena, sphalerite and pyrite which fill tension fractures, form envelopes around small duplexes of sheared, silicified phyllite and occur in the matrix of a large pod of manganese-stained quartz-sulphide breccia.

Concordant, finely banded sphalerite, galena, siderite and minor sulphosalts reach an aggregate thickness of up to 15 m. Lateral continuity is limited and mineralization often terminates abruptly against barren or weakly mineralized limestone. However, sedimentary structures which resemble graded bedding and scouring appear to be preserved in the layered sulphides.
An epigenetic replacement origin is clearly indicated for at least the discordant mineralization on the McMillan property. J. Morin (Department of Indian And Northern Development) suggested that the McMillian deposit is similar to known replacement-type deposits of the Park City district, Utah. This is consistent with a lead isotopic age of 100 million years obtained for galena samples taken by P. Vaillancourt in 1981 and analysed under C.I. Godwin at University of British Columbia (Godwin et al, 1988). Fine banding and other structures in the layered sulphides have been variously interpreted as evidence of a syngenetic origin, or faithful selective replacement of clastic carbonate horizons.

The 1990 program tested the property for bulk tonnage gold potential, based on its proximity to the Hyland Gold deposit (Minfile Occurrence 095D 011). Soil sampling on the east side of the claim block outlined an 1100 x 700 m arsenic anomaly open to the east and south. Bulldozer trenching uncovered brecciated limonitic and pyritic quartzite and sheared graphitic quartzite which returned anomalous arsenic values (82 to 3298 ppm). However, no significant gold values were reported.