The Sunset occurrence is located on an adit, approximately 3 kilometres south of Germansen Landing, just south of the junction between Germansen River and Plughat Creek (near a large open pit of a placer operation) (Open File 1989-12).
This occurrence is hosted by the Mississippian to Permian Cooper Ridge Group. The Cooper Ridge Group in this area has been included as the uppermost sequence of rocks belonging to the Cassiar Terrane (Bulletin, in preparation). The Cooper Ridge Group is composed predominantly of grey to dark grey or black, rusty weathering, thin bedded, wavy to platy argillites. The argillites may grade into slates or phyllites with cleavage becoming the dominant planar fabric (Bulletin, in preparation). At this location, the Cooper Ridge Group is found within the right-lateral Manson fault zone, a northwest- striking fault of probable Cretaceous to Tertiary age (Bulletin, in preparation).
The entrance to the adit is now near the southwest part of an old placer pit which has exposed numerous quartz veins. These veins vary from 10 centimetres to 4 metres in width and are fairly continuous. Two sets of quartz veining have been observed with one set being linear and concordant with foliation, which strikes 105 to 128 degrees and dips steeply to the southwest. The other set is discordant, fractured, exhibits pinching and swelling, and strikes between 020 and 045 degrees. The concordant veins contain chalcopyrite, galena, sphalerite and pyrite.
The vein within the adit is 3 to 3.65 metres in width, striking northwest for a distance of 37 metres. This vein contains pyrite, chalcopyrite and some malachite staining. An assay of vein material yielded trace gold, 21 grams per tonne silver and 1 per cent copper (Bulletin 1, page 59). A grab sample from one of the veins from the pit analysed 0.066 gram per tonne gold, 52 grams per tonne silver, 1.60 per cent copper, 0.0337 per cent lead, 0.0690 per cent zinc and 8 grams per tonne mercury (Open File 1989-12). This sample was taken from a concordant vein and is bounded by Cooper Ridge Group quartz-rich phyllites and argillites.
