The region in which the Uncha Lake showing occurs is within the Intermontane Belt, underlain dominantly by Lower to Middle Jurassic volcanic and sedimentary rocks of the Hazelton Group. These assemblages are overlain by the Eocene to Oligocene Ootsa Lake Formation (Nechako Plateau Group) and Miocene plateau basalt. Intruding Lower Jurassic rocks of the Hazelton Group in the northeastern part of the map sheet is a belt of granodiorite, diorite and quartz diorite plutons of the Lower Jurassic Topley intrusive suite. Felsic plutons of probable Cretaceous age intrude both Lower and Middle Jurassic Hazelton strata.

The Ootsa Lake rock comprises mainly felsic volcanic rocks and their epiclastic derivatives. The Uncha Lake perlite showing occurs within rhyolite of this group on Dayeezcha Mountain. The perlite dips 10 to 30 degrees south and is 7.6 to 23.0 metres thick. The perlite is interbedded within light to dark grey porphyritic rhyolite layers 2.0 to 9.0 metres thick. The perlite is light grey to pale greenish-grey, some perlitic glass occurrences in the area are resinous brown.

WORK HISTORY

Originally staked in 1953 by C.S. Powney and J. Rasmussen of Fort St. James and their associates, the Uncha Lake perlite prospect has been explored by trenching and limited laboratory processing tests. Trenching across the claim group indicated 3 main showings.

British Columbia Minister of Mines reports indicate that in 1955, Technical Mines Consultants Limited exposed nineteen trenches at approximately 45 metre intervals exposing over 2438 metres of bedrock. Six mineable perlite layers along a zone 850 metres long and 500 metres wide were exposed. Depth of overburden increases to the northeast making further trenching impractical. The company reported that the layers were "irregular in width and attitude, lying interbedded in a folded series of rhyolites striking generally northeast and dipping about 70 degrees to the southeast". The last trench to the southwest end of the workings exposed "three strong layers of perlite". Evidence at the time indicated that the zone extends several hundred feet farther to the southwest.

James (Annual Report 1955, page 97) reports the maximum exposed width of at least two layers exceeds 45 metres, and that in some places interbedded rhyolite is sufficiently narrow to permit practical open-pit mining of two or more layers from one pit.

In 2004 or 2005, Harold Oppelt and associates did a systematic sampling of the entire claim structure with random samples taken. They collected 36 rock samples (Assessment Report 27964). In 2006, Oppelt collected 25 rock samples (Assessment Report 28835). In 2010, test sampling was done in order to outline the perimeters of the perlite occurrences for future drilling. At this time Harold Oppelt collected 16 rocks from the Uncha occurrence (Assessment Report 32272).