The GS-25 occurrence is located about 6 kilometres east of the South Unuk River and 3 kilometres south of Sulphurets Creek. The area is underlain by mafic and intermediate volcanic rocks of the Middle Jurassic Salmon River Formation, Hazelton Group.
In 1987, Bighorn Development Corporation collected several rock samples in the area. Sample GS-25 assayed 0.93 grams per tonne gold and 35.66 grams per tonne silver (Assessment Report 17404). No description of the sample was given.