The Rainy Monday showing was discovered by British Columbia Geological Survey field crews in 1992. The discovery showing is located on the west side of a north-trending ridge where a resistant, rusty weathering outcrop of massive to semimassive sulphide protrudes from a scree slope. The host rocks are typical of the middle Tats member of the Late Triassic Tats group. Pillowed flows crop out to the north and south of the sulphide zone and calcareous siltstone talus occurs upslope to the northeast. The host stratigraphy is contained within a northwest-trending belt that is offset by an east-striking fault north of Tats Lake. The most likely fault restoration solution places the Rainy Monday deposit on strike with the mineralogically similar Tats showing (114P 003), thus increasing the overall length of the prospective horizon.
The Rainy Monday discovery showing dips steeply to the northeast and is about eight metres wide. Within the zone are lenses of porous iron oxide and hydroxide five metres wide that locally contain remnants of coarse-grained pyrite and partly oxidized chalcopyrite stringers up to 20 centimetres thick. Mineralization persists over a slope distance of 30 metres but the strike continuation of the zone is lost beneath vegetation and scree to the west and east. Although the surface showing is extensively weathered and ozidized, samples of coarse-graine dpyrite and chalcopyrite contain copper concentrations up to 13.5 per cent and gold up to 0.72 gram per tonne.
The southeast strike of the discovery showing suggests that the host stratigraphy may crop out on the east side of the ridge along scree slope. Several rusty weathering, resistant knobs protrude from the scree slope and each of these exposures were found to be oxidized massive to semimassive sulphide similar to the discovery showing. The lenses are interbedded with intensely chloritized flows and calcareous, carbonaceous siltstone and argillite. The host stratigraphy strikes north-northwest and dips steeply to the northeast. The oxidized sulphide lens occurs within a northwest-trending zone that is over 100 metres wide. A mineralized zone comprises stringers and lenses of massive chalcopyrite and pyrite up to 30 centimetres thick. Some of the lenses are cut by postmineral mafic dikes or sills which may have recrystallized an original fine-grained protolith. Grab samples collect by British Columbia Geological Survey personnel contained up to 20.2 per cent copper, 2.4 grams per tonne gold, and 39 grams per tonne silver.
Mineralization within the southeastern zone has a visible vertical extent of 150 metres and appears to continue beneath lateral moraine near the valley floor. Assuming that the discovery showing and lenses exposed on the east-facing scree slope are at the same stratigraphic level, the Rainy Monday mineralized zone has a strike length of at least 600 metres, is up to 100 metres thick and extends down dip at least 150 metres. These dimensions suggest the deposit has significant tonnage potential.
