The McNeil property is entirely underlain by rocks of the Helikian Aldridge Formation (Purcell Supergroup) and predominantly comprise siltstones and quartzites. The sediments are relatively flat-lying and are thinly to very thickly bedded. A gently north-northeast plunging syncline is centred in the south part of the property. Lower Aldridge Formation rocks have been mapped on the east limb of the syncline, immediately north of the northeast trending Moyie fault. The west limb of the syncline is cut by the north trending McNeil Creek fault, a major steeply west dipping(?) normal fault with vertical displacement in the order of 1000 metres. Several thick, regional gabbro intrusions of the Proterozoic Moyie Intrusions also occur on the property. The uppermost of these, the "Hiawatha" sill, has been intersected in several diamond-drill holes.
Mineralization is of two types: 1) stratabound base metal sulphides developed at the Lower-Middle Aldridge Formation contact; and 2) a series of mineralized quartz veins in Middle Aldridge Formation rocks.
The stratabound mineralization generally occurs as banded sphalerite and as fracture-fillings and disseminations. A best drill intersection assayed 1.74 per cent zinc over 40 centimetres (Assessment Report 19989).
A series of sulphide-mineralized quartz veins occur in hydrothermally altered lower Middle Aldridge Formation quartzites and siltstones, just above the hanging wall of a regionally extensive, thick gabbro sill, on the west limb of the McNeil syncline. The veins occur near the gabbro hanging wall contact in an orthogonal set of fractures, of which two are steeply dipping and one is relatively flat. Wallrock adjacent to the vein zones are commonly altered. Vein widths range from a few centimetres to 1.5 metres. The veins carry galena, sphalerite, chalcopyrite and pyrite with gold and silver values. Cerussite and pyromorphite are extensively developed from weathering of galena, and chalcopyrite is typically oxidized to malachite; sphalerite has been weathered to smithsonite. The veins are oriented at approximately 120 degrees and are steeply dipping.
The best intersection of vein material assayed 13.99 per cent lead, 2.11 per cent zinc and 137.8 grams per tonne silver over 0.65 metre (Assessment Report 19989). There is a spatial and genetic relationship between the quartz veins and the "Hiawatha" sill, with the veins occurring near the juncture of feeder dike(s) and the gabbro sill.
Sedex Mining Corp. drilled the property in 1998. See McNeil (082FSE109).