The Lad (Lass) occurrence is located on an east-northeast–facing slope in southern headwaters of Gautschi Creek, a north-flowing tributary of the Sikanni Chief River and approximately 4.1 kilometres west-northwest of Mount McCusker.

Regionally, the Mount McCusker area is underlain by three thrust sheets of Paleozoic sediments. The westernmost sheet comprises Cambrian to Ordovician Kechika Group limestone and argillaceous limestone. This is thrust over a narrow panel of Silurian Nonda Formation dolostone and sandstone and an unnamed Upper Ordovician sandstone, dolostone, and shale unit. This, in turn, is thrust over a conformable sequence of Silurian Nonda Formation dolostone and sandstone, Lower Devonian Muncho-McConnell Formation dolostone and Lower to Middle Devonian Stone Formation dolostone. This last panel hosts the mineralization.

Mineralization, hosted within Nonda Formation dolomite breccia, consists of blebs, patches, discontinuous veinlets, and disseminations of sphalerite (with rare galena and pyrite) in sparry dolomite cement. Two areas of mineralization (the North and South zones) separated by 450 metres of talus are believed to be continuous, giving a total strike length of 750 metres. Minor lead and zinc mineralized quartz veins are present up to 20 metres below the breccia unit.

In 1973, the average grade from surface chip samples is 2 to 3 per cent combined zinc and lead whereas individual outcrop samples yielded up to 3.72 per cent zinc and 0.05 per cent lead over 15.9 metres (sample S-3) from the North zone and 3.17 per cent zinc with 0.81 per cent lead over 2.1 metres in the South zone (Sample S-25, Assessment Report 4865). Also at this time, talus samples from the North and South zones yielded an average of 0.21 and 0.05 per cent lead with 2.45 and 3.89 per cent zinc over 54 and 75 metres, respectively (Assessment Report 4865).

In 1974, the best mineralized drill intersections, collared in the North and South zones, were 3.58 per cent zinc over 1.03 metres in hole Z-74-5 and 1.74 per cent zinc over 0.40 metre in hole Z-74-4, respectively (Assessment Report 5328).

Work History

In 1973, British Newfoundland Exploration Ltd. completed a program of geological mapping and geochemical (rock, silt and soil) sampling on the area as the Lad, Lass, Brin, JR, Lau and Toll claims. The following year, 14 diamond drill holes, totalling 950.0 metres and drilled from five sites, were completed but failed to indicate any significant continuity of mineralization along strike or down dip from the surface exposures. In 1975, British Newfoundland completed a further program of geological mapping and silt sampling on the Lad and Lass claims.