The Bruno showing area is underlain by the north-trending contact of andestic volcanics of the Hazelton Group (on the west) and marine sedimentary and volcanic rocks on the east.

Mapping in 1990 by Granges Inc. outlined a wedge of sedimentary rocks of flysch association including argillites, conglomerates, volcanic mudstones and arenaceous tuffaceous sedimentary rocks. Portions of this sequence are sheared and brecciated, containing abundant quartz-carbonate-sulphide mineralization including pyrite as well as traces of sphalerite, galena and chalcopyrite. The pillowed andesites, agglomerates and finer grained related tuffaceous rocks which occur to the south and west appear to be in fault contact with the sedimentary wedge. This trend is semi-parallel to the trend of narrow sphalerite-rich breccia veins carrying up to 15.7 grams per tonne (Assessment Report 20993) which can be found to the south along the western edge of the north-south trending ice lobe. One such vein has been found to reach a width of about 30 centimetres and is traceable for about 50 metres to the edge of the ice. In addition to these east-west mineralized veins, several north-south trending zones of shearing and brecciation can be observed at the toe of the ice lobe.

Refer to Unuk (MINFILE 104B 083) for related details and property work history.