The area of the Rainbow 3SE showing is underlain by a stock of granodioritic quartz feldspar porphyry of the Late Cretaceous Bulkley Plutonic Suite. The stock is known as the Sunsets stock and intrudes Basalt to andesite to rhyolite volcanic rocks of the Lower Jurassic Telkwa Formation, Hazelton Group.

In 1990/1991, Skeena Resources collected two rock samples from the southeast area of the Rainbow 3 claim. Sample WR-44 was taken from sub-angular andesite boulders which were reported to contain up to 7 per cent disseminated magnetite and up to 3 per cent pyrite and minor chalcopyrite. This sample assayed 0.63 gram per tonne gold, 3.4 grams per tonne silver and 10.3 per cent zinc. Values in lead and copper were not anomalous (Assessment Report 21765). Sample WR-45 about 200 metres north of WR-44 was from an andesite outcrop containing disseminated pyrite, chalcopyrite and bornite. This sample assayed 0.2 gram per tonne gold, 31 grams per tonne silver, 1.77 per cent copper and 0.04 per cent zinc (Assessment Report 21765).

Refer also to King (093L 041) for general information on the El Toro property, a large property that was worked by of Lions Gate Energy Inc from 2007 to present (2015) and encompassed the Sunset Basin area which contains this showing.

Refer to Fly (093L 045) for related details.