The region in which the showing occurs is within the Inter- montane Belt, underlain dominantly by Lower to Middle Jurassic volcanic and sedimentary rocks of the Hazelton Group. These as- semblages are overlain by the Upper Cretaceous to Lower Tertiary Ootsa Lake Group and Miocene plateau basalt. Intruding Lower Jurassic rocks of the Hazelton Group in the northeastern part of the map sheet is a belt of granodiorite, diorite and quartz diorite plutons of the Lower Jurassic Topley intrusive suite. Felsic plutons of probable Cretaceous age intrude both Lower and Middle Jurassic Hazelton strata.

The Topley intrusive suite in the northeastern part of the map sheet is host to a number of mineral occurrences, mainly molybdenite. The Hidden occurrence, however, consists of pyrite-galena mineralization within an 8 metre wide quartz vein in sheared Topley granodiorite. The vein, which strikes 025 degrees and dips 60 degrees west, is oxidized in places. Anomalous gold and silver values accompany the sulphide mineralization.