The Gran 15 area is underlain by the contact of a Middle to Late Triassic quartz dioritic pluton and sedimentary rock of the Devonian to Permian Stikine Assemblage.

The main rock type encountered in 1989 was a medium-grained granodiorite, locally migmatitic, with abundant bull white quartz veins up to 30 centimetres in width. These quartz veins were typically barren but where mineralized carried up to 2 per cent blebby chalcopyrite and 5 per cent disseminated pyrite, with 2 to 3 per cent patchy epidote. The Gran 15 showing is one such quartz vein where the second highest assay of 1989 on the Gran 15 claim was obtained. The sample was taken from a white quartz vein in granodiorite that yielded 0.105 per cent copper, 0.3 gram per tonne silver and 3 parts per billion gold (Sample 31448, Figure 4.1, Assessment Report 19059). The vein was reported to contain 3 to 4 per cent malachite and a trace of chalcopyrite.

In 1989, the Gran 15 property consisted of one claim totalling 20 units and was owned by Homestake Mineral Development Company and Equity Silver Mines Ltd. Work on the property involved prospecting and the collection of 11 rock samples.

See Gran 15 South (104G 241) for related information and a more detailed work history of the Gran 15 property area.