The IN 41 region is underlain by Pennsylvanian andesite and basaltic augite porphyry of the Stikine Assemblage that have been intruded by a stock of quartz monzonite, possibly related to Middle Jurassic Three Sisters Plutonic Suite or the Middle to Late Triassic Stikine Plutonic Suite. Andesite is the dominant rock of the assemblage and varies from tuffaceous to crystalline, contains minor beds of chert and limestone and is frequently dioritic near the quartz monzonite contact.

Chalcopyrite, magnetite and pyrite occur in shears and shattered zones within andesite near a north-northeast trending fault. Some chloritic alteration is noted. Quartz monzonite also hosts some chalcopyrite and magnetite. Quartz veins carrying only pyrite are also present in the area of interest. Limestone float is noted in the area and dolomitic carbonate is mapped regionally to the immediate east.

Refer to IN 32 (104G 080) for details of exploration work completed on the In, Out and C claims by Hecla Operating Company, from 1971 to 1973 inclusive.