The “Three Sisters North” occurrence is hosted within Middle Jurassic (and/or Early Cretaceous?) Three Sisters Plutonic Suite rock consisting of the central felsic phase. It consists of massive, equigranular (2 to 3 millimetres) biotite and lesser hornblende-biotite quartz monzonite and quartz monzodiorite, locally with potassium-feldspar phenocrysts.

The rocks are intensely veined (roughly 5 per cent by volume) in a several-metre wide interval. The interval hosts one 10-centimetre-wide east-southeast oriented, steeply north dipping, epidote plus actinolite, plus sulphide vein. The assay results for this vein are 0.36 per cent copper, greater than 0.02 per cent tungsten and slightly elevated uranium (11BVA30-216 in Table 2, Fieldwork 2011).

The Three Sisters North showing was found during a 2011 fieldwork program completed by the BC Geological Survey Branch. One rock sample was analyzed, and the area was mapped.