The Mario occurrence is located in a former logging road blast pit on the south side of the Adam River, approximately 3.6 kilometres south west of its junction with Compton Creek.

The area is underlain by Upper Triassic Vancouver Group rocks comprised of a thick sequence of tholeiitic basalts with minor intercalated sediments of the Karmutsen Formation. The Vancouver Group rocks are in fault contact with the underlying Permian Sicker Group sediments. Granodiorite of the Jurassic Island Plutonic Suite, intrudes the older rocks.

The occurrence is underlain by Karmutsen volcanic rocks which are crosscut by a few east striking quartz feldspar porphyry and feldspar porphyry dikes, presumed to be related to the Island Plutonic Suite. Several north west and east striking faults cut the rocks in the central claim area.

Locally, pyrite, pyrrhotite, chalcopyrite and molybdenite occur in quartz veins and veinlets in volcanic rocks. Slightly elevated values for silver and mercury in soils are reported in the area of the quartz veining (Assessment Report 13589).

In 1985, Canamin Resources completed a program of prospecting, soil sampling and trenching.