The area is underlain by metamorphic rock of the Mesozoic and/or Paleozoic Wark Gneiss and greenstone of the Lower Jurassic Bonanza Group. A discontinuous limestone horizon extends along a northwest trend and is thought to be correlative with the Upper Triassic Quatsino Formation, Vancouver Group. The Wark Gneiss comprises mainly massive and gneissic metadiorite, metagabbro and amphibolite (see Willoron 1-3,9,10 - 092B 056). The Wark Gneiss is possibly the metamorphic equivalent of a mafic unit of either the Paleozoic Sicker Group or the Upper Triassic Karmutsen Formation (Vancouver Group); the latest metamorphism took place in the Jurassic.

Numerous magnetite showings occur in the area as lenses and fracture-fillings in all rock types, but mainly in association with limestone lenses. Associated skarn minerals are reported to be garnet, epidote and diopside.

The Star deposit consists of two "veins" of magnetite and pyrrhotite (about 50 per cent of each) with pyrite and minor chalcopyrite. The veins are about 12 metres apart striking north to northwest and dipping 75 to 80 degrees westward. The west vein is about 3 metres wide, the east one about 6 metres and they extend for up to 30 metres along strike. The veins are thought to be inter- connected. About 15 metres to the north of the east vein, magnetite is exposed for a distance of about 6 metres, but the dip and strike are not apparent. In Aho's 1961 report the wallrocks are reported to be skarn and greenstone, but his map of the property indicates the showing to be hosted by limestone. A 1.2 metre chip sample assayed 4.80 grams per tonne gold, 12.00 grams per tonne silver and 0.20 per cent copper; a grab sample assayed 56.72 per cent iron and 0.15 per cent copper (Aho, 1961).

By 1902, 65 metres of tunnelling was done beneath the showing. The rock cut in these workings was chiefly diorite and diabase, with occasional streaks of limestone. No ore was intersected (Minister of Mines Annual Report 1902, page 222).

Thirty metres to the southeast of Showing 12, five showings of pure magnetite outcrop or float occur over an area of 15 metres in diameter.