Quartz diorite and lesser quartz monzonite of the Early to Middle Jurassic Island Plutonic Suite occupies most of the Bus occurrence area. In the northeast are volcanic rocks of the Lower Jurassic Bonanza Group consisting of intercalated and thinly-bedded andesites with minor rhyolite and dacite. In the southeast portion are massive and commonly amygdaloidal or porphyritic basalts correlated with the Upper Triassic Karmutsen Formation (Vancouver Group). Quartz feldspar porphyry and feldspar porphyry dykes, from 5 to 20 metres wide, intrude both the Bonanza Group and the quartz diorite, being more common in the former.

Steeply dipping faults and shear zones transect all rock types. Pyrite disseminations, stringers and small pods associated with quartz patches, veinlets and stockworks are often found within the silicified shear and fault zones. These mineralized faults are usually adjacent to or near porphyry dykes in Bonanza Group rocks. Sparse arsenopyrite was observed in one shear zone; minor malachite and chalcopyrite in another. A grab sample from a shear zone assayed 9 grams per tonne silver (Assessment Report 8719).

A pit exposes lenses and stringers of pyrite-chalcopyrite- magnetite +/- pyrrhotite within a shear zone striking 165 degrees and dipping 42 degrees east. The shear is hosted in Karmutsen Formation basalt. Epidote, chlorite, calcite and minor actinolite were also observed in the shear. Grab samples from this zone assayed up to 1.12 per cent copper (Assessment Report 4357).