The Mount Prince southeast showing occurs in an area underlain by Upper Triassic Takla Group volcanic rocks. The Takla Group is in fault contact to the west with mainly Paleozoic rocks equivalent to the Cache Creek Group. The fault separating the two groups is the Pinchi Fault, a major structural feature marking the boundary of the Cache Creek and Quesnellia terranes. Adjacent to the fault within Takla Group rocks are a number of mercury occurrences of which some have, in the past, been worked.

The Mount Prince southeast showing consists of small amounts of cinnabar in carbonatized and sheared mafic volcanics of the Takla Group. The cinnabar commonly occurs within quartz stringers.