Regional mapping indicates the area is underlain by Mesozoic and older sediments and volcanics which have been intruded by granitic rocks of an Early Jurassic plutonic suite

The oldest rocks consist of a thick sequence of weakly metamorphosed siltstones and argillites of the Devonian to Permian Stikine Assemblage. Overlying this sequence are black shales, siltstones, greywacke and conglomerates of the Upper Triassic Stuhini Group. .

Intruding the Mesozoic rocks are Jurassic to Tertiary plutonic rocks which range in composition from syenite to diorite. Contact metamorphism consists of large zones of hydrothermal alteration with the formation of some migmatites and cataclasites.

On the property, the dominant sedimentary rock type consists of black to grey, foliated and well-bedded argillaceous siltstone. The siltstone grades into well-indurated, poorly foliated and well-bedded quartz sandstone. Other sediments include massive chert and inter- bedded chert. The volcanics consist mainly of mafic volcanic tuffs and breccias with dark grey to green mafic volcanic flows which in- clude feldspar porphyry volcanic flows.

An orthoclase porphyry stock intrudes the sediments and volcanics near the southwestern corner of the Hemlo West 13 claim. This small stock is characterized by 1 to 3 centimetre long orthoclase pheno- crysts in a medium to fine-grained plagioclase-pyroxene matrix. Alteration associated with this intrusion consists mainly of chloriti- zation and epidotization.

Large areas of this intrusive body were reported to carry dis- seminated chalcopyrite with associated gold values. Widespread disseminated and fracture-controlled pyrite and chalcopyrite occur in the surrounding rocks. Isolated quartz veins with minor pyrite and chalcopyrite mineralization are common. At the north end of the Hemlo West 13 claim, several narrow quartz veins were mapped crosscutting the main creek. The main creek follow a fault which cuts argillaceous siltstone, tuff and quartz sandstone. In 1986, a chip sample taken across a 20 centimetre vein assayed 7.097 grams per tonne gold and 2.3 grams per tone silver (Assessment Report 15336).

Refer to Gregor (104B 357) for further details and a common work history.