The Cyathid Mountain occurrence is located west of the Blue River, approximately 23 kilometres south of the Yukon-British Columbia border, about 146 kilometres north of the community of Dease Lake. In 1987, the Cyathid Mountain showing was discovered in the course of mapping by the Geological Survey Branch.

The showing occurs in a strong quartz-calcite stockwork zone that cuts Lower Cambrian archeocyathid-bearing dolomite and limestone of the Rosella Formation (Atan Group). The 70 by 15 metre zone has a strike of 030 degrees and dips 65 degrees northeast. Mineralization consists of very minor chalcopyrite.

The Cyathid Mountain stockwork grades into a zone of brecciation and calcite spar 1.5 kilometres to the northeast. This feature points to the importance of structural control for this kind of mineralization. The showing may be related to an episode of late Cretaceous to Eocene intrusion and lead-zinc-silver mineralization (Fieldwork 1987).