The area is underlain by hornfelsed sediments, argillite, quartzite and chert and volcanics, andesite breccia and greenstone tuff of the Mississippian to Jurassic Bridge River Complex (Group). An oblong-shaped stock, 1.5 kilometres by 2 kilometres long, intrudes the sediments and volcanics. The Index stock is mainly granodiorite, grading to biotite granite and quartz monzonite. It is related to a larger Tertiary-Cretaceous intrusion located a kilometre east of the Phair Creek fault. Small andesite dykes and a swarm of biotite lamprophyre dykes cut through the stock.

Molybdenite occurs mainly within the core of the Index Stock, which is fine-grained and aplitic. The molybdenum is seen in northerly trending shears and disseminated on fractures. The highest concentrations are in a 1-metre wide lenticular zone as clots of solid fine-grained crystals or rosettes which assay up to 7 per cent MoS2 and have low grade (1.3 grams per tonne) gold values. The molybdenum is associated with quartz and sericite with kaolinitized orthoclase. Molybdite, an oxide of molybdenite, characterizes the surface of enriched zones. In 1916, 7.4 tonnes of material grading 15.01 per cent MoS2 was extracted (Minister of Mines Annual Report 1949, page 113).

Uraninite has been reported in the mineralized outcrops; however, assays are low, the highest being 0.0085 per cent U3O8 (Minister of Mines Annual Report 1949, page 114).

During 2007 through 2010, Galliard Resources Corp. examined the area as the Index and Enterprise properties.