Banks Island is situated near the western margin of the Coast Plutonic Complex. The island is underlain by Tertiary to Cretaceous granitic rocks that vary in composition from gabbro to quartz mon- zonite. The granitic rocks host roof pendants of Permian (?) or older metasediments consisting of crystaline limestone/marble, pelites and skarn.
The Isla Mist property is underlain by granodiorite and quartz monzonite phases of the Coast Plutonic Complex. Locally, the biotite quartz monzonite or granodiorite is fine-grained, light colored and hosts abundant quartz veins infilling a strong fracture pattern. Many light-colored dykes, characterized by muscovite, quartz and white feldspars, cut the fine quartz monzonite unit.
Major fault directions on the property are 295 degrees and 045 to 050 degrees, with extensive fracturing controlling sheeted and stock- work veining.
Three mineralized areas are known to occur on the property and all are hosted by the fine quartz monzonite unit. The unit has associated silica-sericite alteration with stockwork and sheeted veining. Majority of the veins strike between 110 degrees and 140 degrees but the strong "Boutwell Vein" subparallels a 090 degree structural trend.
Veins vary from 1 to 2 centimetres to over 1 metre and several generations of veins are present. Early veins are barren and later veins host chalcopyrite, pyrite and molybdenite with local scheelite concentrations (refer to Tungsten 103G 044 and Isla Mist 103G 045).
Mineralization in the Boutwell vein was exposed in 1985. Chalco- pyrite is concentrated near the centre of the quartz vein with molyb- denite occurring mainly on slickensided vein margins. Magnetite and pyrite are present and account for the oxidation and abundant limonite staining.
In 1987, a chip sample across 1.2 metres of the Boutwell vein assayed 0.037 per cent molybdenum, 1.6 per cent copper, 0.11 per cent zinc, 40.4 grams per tonne silver and 0.08 grams per tonne gold (Property File: Christopher, P.A., 1988).