The area is underlain by Paleozoic rocks which consist mainly of fine-grained, dark clastic sedimentary rocks and intercalated volcanic rocks. They have been intensely folded and sheared with the consequent development of slaty cleavage and foliation. Fine-grained secondary mica has formed in most of the rocks to give them a platy, phyllitic texture. The volcanic rocks have been metamorphosed to greenstone and chlorite-amphibole schist.

On the south side of the Sittakanay River the Paleozoic rocks are intruded by a Tertiary-Cretaceous biotite-hornblende quartz monzonite stock which is thought to be correlative with the Sloko Group volcanics.

The Highland Boy group of 6 claims is reported to be one of the oldest groups in the Taku River area. The property is underlain by quartz-mica schist, quartzite, argillite, and slate which strike about 345 degrees and most commonly dip moderately to the east. The quartzites and quartz-mica schists are intensely folded and give the impression of a succession of small, nearly isoclinal folds. The formation carries large masses of barren quartz, the largest being 60 metres long and up to 10 metres wide (oriented 210/37W) as well as veins which carry massive pyrite and a vein of galena with arsenopyrite on which most of the work was done. Quartz sweats five to six centimetres wide occur parallel to foliation.

A mineralized shear zone has reportedly been traced for 60 metres and varies in width from 2.5 centimetres up to 1 metre of discontinuous mineralization. The shear zone strikes 035 degrees and chips vertically.

In 1932, a sample from the north end of a galena-arsenopyrite vein was reported to assay about 18 grams per tonne gold. Another pyrite, galena, and arsenopyrite vein about 2.5 centimetres wide was reported to have returned silver values. West of these veins is about 0.9 metres of quartz and pyrite which is reported to contain 2.4 grams per tonne and 3.3 grams per tonne gold (GSC Memoir 248).

A reported 23 metre long adit explored the mineralized vein. A shallow four to six metre deep shaft also cuts into it. Mineralized tailings from the shaft, sampled in 1991, reportedly assayed 10.4 grams per tonne gold, 35.4 grams per tonne silver, 0.99 per cent lead and 22.69 per cent arsenic (Assessment Report 22037).

Recent work also explored six old trenches on the showing with a sample of fault gouge from trench #1 assaying 8.05 grams per tonne gold, 475.2 grams per tonne silver, 6.88 per cent lead, and 24.27 per cent arsenic (Assessment Report 22037).

In 1990, Stow Resources Ltd staked the Highland Girl claim to cover the old Highland Boy occurrence and limited soil and rock sampling was done. In 1991 Stow collected twenty-eight rock samples of which five were grab, three chip and twenty float (from tailings). Geologists from a BC Geological Survey Branch field mapping crew visited the Highland Boy and sampled the showing (Fieldwork 1993, page 195).