The Selwyn lake area is underlain by granite gneisses of Archean age, which include two separate belts of high grade metasediments. The southern belt consists of metasediments (including meta-arkose). The northern belt contains large bands of massive amphibolite interlayered with metasediments. The amphibolite is interpreted to be a meta-gabbro. To the east of the area and parallel to Selwyn Lake, the granite gneisses are affected by mylonitization.
Massive sulfides are found in the amphibolite and interlayered biotite quartzite and define the Selwyn Lake Copper showing. The sulfides consist of pyrite, pyrrhotite and chalcopyrite, and are found exposed over a distance of more than 1,000 metres. Chemical analysis of selected grab samples reveal copper contents of up to 0.1%. Analysis also show the presence of minor gold associated with the mineralized zone.
The 17 mineral occurrences of the Leland Lakes area include two showings. The Myers Lake Gold showing is defined by a grab sample with a gold content of 200 ppb and is probably related to a basic intrusion. The Myers Lake Radioactive showing is a 1 by 15 m area of Slave Granite with radiation of up to 2000 total counts per second.