Lower Jurassic Hazelton Group volcanics of the Telkwa Formation are comprised of andesitic to rhyolitic flows, tuff and breccia. The Fog prospects is hosted by one of two quartz-sericite-pyrite (phyllic altered) zones within the southern part of the Sunsets stock, a Late Cretacious quartz-feldspar porphyry stock of the Late Cretaceous Bulkley Plutoinic. The intrusion is an epizonal body which produced a domal effect on the Hazelton rocks.

Locally, the volcanics are comprised of fragmental tuff with minor intercalated flows. The volcanics are moderately to intensely hornfelsed as the intrusive margin is approached. In some areas the volcanics are skarned producing calc-silicate minerals and garnet with or without disseminated chalcopyrite and magnetite. Disseminated pyrite in the volcanics increases towards the contact.

Hydrothermal alteration in the core area of the intrusive produced argillic alteration due to the breakdown of feldspar. As well, widely spaced sub-parallel quartz veins, ranging between 2 to 5 centimetres in widths host pyrite, chalcopyrite, and molybdenite.

Two quartz-sericite zones host pyrite, molybdenite, and minor chalcopyrite along joints and fractures. One zone is called Fog and the other is Fly (093L 045).

Quartz-pyrite molybdenite chalcopyrite veins 2 to 5 centimetre wide and trending predominantly northeasterly and dipping southeast are associated with the alteration zones. Potassic alteration, suggested by pink feldspar alteration envelopes along fractures and quartz veins, is reported at a lower vertical level beneath the sericitic zones.

In 2008, maximum values from the Fog phyllic alteration zone were 0.93 per cent copper with 48.2 grams per tonne silver and 0.013 per cent molybdenum from quartz sulphide veinlets and a 1 metre chip sample yielded 0.083 per cent copper (Assessment Report 30731). Previous results from the southern margin of the phyllic alteration returned higher values with 0.252 per cent molybdenum and 0.01 per cent copper from a 0.5 metres channel sample with maximum results of 0.645 per cent molybdenum with 0.08 per cent copper (Assessment report 8444).

See Fly (093L 045) for details of a common work history.