The area is underlain by Lower to Upper Cretaceous Pasayten Group sediments which are comprised of altered, fractured and fissured sandstone, conglomerate and pelite. These are intruded by diorite of the Late Jurassic and Early Cretaceous Eagle Plutonic Complex. To the north of the showing, the Upper Oligocene-Lower Miocene Coquihalla Formation comprised of basalt, rhyolite, tuff and agglomerate, caps Coquihalla Mountain.

The Gold Mountain showing consists of a quartz vein, ranging from 5 to 30 centimetres in width, infilling a fracture in the Pasayten Group rocks, striking 090 degrees and dipping slightly to the south. The vein is faulted and was developed by a 38.1-metre adit and two opencuts. The vein hosts galena, chalcopyrite, arsenopyrite, and pyrite with minor tetrahedrite and bornite.

In 1913, a 25-centimetre sample taken across the vein yielded 0.68 gram per tonne gold and trace silver. A hand-picked sample of high-grade material analysed 14.40 grams per tonne gold, 685.7 grams per tonne silver and 4.9 per cent copper (Minister of Mines Annual Report 1913, page 233).

In 1984, silicification and pyritization was found to be associated with east-trending faults. Gold and silver values are associated with the quartz infilling.