The area of the Pyrrhotite Creek occurrence is underlain by basalt and massive to locally bedded chert of the Permian to Jurassic Hozameen Complex. Basalt-chert contacts are steeply dipping and probably faulted. Small intrusions of diorite to granodiorite of unknown, but probable Tertiary age occur in the basalt. A fault striking 015 degrees along Pyrrhotite Creek truncates a 120 degree striking fault that passes through the Giant Creek area. Monger has mapped another west-northwest striking fault in the valley north of the property (GSC Map 12-1969).

Over several square kilometres, the basalt is altered and veined. Alteration consists mainly of silicification and lesser sericitization. Three main types of mineralization are reported to occur in the vicinity. These include skarn, veins and porphyry types.

In 1938, Sargent reported that this showing, extending from the east side of Pyrrhotite Creek eastward, was one of the most promising "replacement" showings in the area (Minister of Mines Annual Report 1938, page F19). Pyrrhotite Creek itself marks a lithologic contact between basalt and chert.

Several skarns with outcrop areas up to 3 metres across are exposed in cuts in altered basalt. The skarns are mainly massive pyrrhotite with 1 to 2 per cent chalcopyrite and very variable quartz (0 to 80 per cent). Some disseminated mineralization also occurs. In 1938, a chip sample taken by Sargent yielded 0.69 gram per tonne gold, 0.5 per cent copper and a trace of silver over 3.35 metres. One locality in the creek bed itself contained mainly pyrrhotite with chalcopyrite but also pyrite and little stibnite.