The Cas occurrence is located 12.5 kilometres southeast of the eastern end of Chuchi Lake and approximately 71 kilometres north-northeast of Fort St. James.

The Cas occurrence falls within the Mudzenchoot halo (Open File 1991-3), an area where the volcanic rocks are silicified and strongly hornfelsed. Fine-grained diorite and megacrystic orthoclase syenite outcrop within the halo (Fieldwork 1990, page 105).

The Cas area is underlain by scattered outcrops of andesite and trachyandesite flows and tuffs of the Upper Triassic Witch Lake Formation (Takla Group) intruded by a monzonite plug and associated dikes (Assessment Report 22179). These intrusions are considered to be coeval intrusive equivalents of the Middle Triassic to Lower Jurassic Takla Group.

The volcanics contain an average of 1 to 2 per cent disseminated pyrite and/or pyrrhotite, commonly associated with epidote, chlorite and carbonate alteration or biotite hornfels. This propylitic suite is prominently developed along the north and west flank of the plug, which also contains the same volume of sulphides. The higher sulphide areas in the volcanics locally contains 2 to 3 per cent disseminated magnetite and specks of chalcopyrite.

In 1987, the Mitzi claim group was staked by Richard Haslinger and, in 1988, Placer Dome completed soil and rock sampling around the Taylor showing. Noranda Exploration Company acquired the Mitzi property from Haslinger in 1989 and worked on it until 1992. They completed geological mapping, soil/rock sampling, an aeromagnetic-electromagnetic survey, ground magnetic and induced polarization surveys and 18 diamond drill holes, including 15 holes on the Main grid (TT claims), 2 holes on the Cas (093N 218) and 1 hole that tested the western extension of the Taylor occurrence (093N 096).

In 1991, Placer Dome Incorporated conducted a program consisting of 16 kilometres of flagged line, geological mapping and a soil and rock sample program. In total, 288 soil samples and 8 rock samples were collected, and no significant targets were located.

In 1992 Noranda drilled hole NA-92-16 in order to test a magnetic and soil copper anomaly on the outer northeast edge of the chargeability zone flanking the Cas monzonite plug (Assessment Report 22895). The hole intersected an interbedded sequence of andesite-feldspar andesite (possibly intrusive) and andesite fragmentals cut by small feldspar porphyry and augite porphyry dikes. Alteration consisted of biotite hornfelsing with pyrite, pyrrhotite disseminations with local propylitic selvages. Sulphide mineralization is less than 2 per cent and dominantly pyrite, epidote is locally present. No significant assays were obtained from this hole.

In 2012, a copper-gold anomaly was discovered approximately 1 kilometre north of the Cas occurrence during a soil sample program. The small number of samples collected in this target area resulted in limited detail of the soil anomaly; diamond drill testing was recommended to determine the bedrock source of the anomaly.