The region in which the Molly 9 showing occurs is within the Intermontane 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 ranges in composition from diorite to alaskite but consists mainly of quartz monzonite and diorite. In the area of the showings two main intrusive phases have been recognized, the Nithi quartz monzonite and the Casey quartz monzonite to alaskite.

Several quartz-molybdenite veins striking at 065 degrees occur within Nithi quartz monzonite over an area of about 400 by 600 metres. Argillic alteration of wallrock is moderate to strong and is accompanied by weak potassic alteration.

For full work history see nearby Nithi Mountain (MINFILE 093F  012) occurrence.