The Tonawanda prospect is at 1300 metres elevation, on small draw south of Fissure Creek; an easterly draining tributary of Ferguson Creek, which flows south into Lardeau Creek at Ferguson.
The mineral occurrence was located in the early 1900s and two adits were driven to explore a vein. In the mid-1950s, there was an unsuccessful attempt to excavate one of the adits and two short holes were drilled to test the mineralized structure at depth. The same ground was prospected as the Fergi #2 claim in the late 1980s, and it was held by St. Patrick Mining Limited in the early 1990s.
The Trout Lake area is underlain by a thick succession of sedimentary and volcanic rocks of the Badshot Formation and Lardeau Group near the northern end of the Kootenay arc, an arcuate, north to northwest trending belt of Paleozoic and Mesozoic strata that is now classified as a distinct, pericratonic, terrane. The arc rocks are bordered by Precambrian quartzite in the east and they young to the west, where they are bounded by Jurassic-age intrusive complexes. They were deformed during the Antler orogeny in Devonian-Mississippian time and were refolded and faulted during the Columbian orogeny, in the Middle Jurassic. A large panel, the "Selkirk allochthon", was later offset to the northeast by dip-slip motion along the Columbia River Fault.
The Badshot Formation is composed of a thick Cambrian limestone that is a distinctive marker horizon in the Trout Lake area. It is underlain by Hamill Group quartzite and it is overlain by a younger assemblage of limestone, calcareous, graphitic and siliceous argillite and siltstone, sandstone, quartzite and conglomerate, and also mafic volcanic flows, tuffs and breccias, all of which belong to the Lardeau Group. The rocks are isoclinally folded and intensely deformed, but only weakly metamorphosed. They occur as intercalated beds of marble, quartzite and grey, green and black phyllite and schist. Fyles and Eastwood (EMPR BULL 45) subdivided the group into six formations (Index, Triune, Ajax, Sharon Creek, Jowett and Broadview) of which the lowermost (Index) and uppermost (Broadview) are the most widespread. The Triune (siliceous argillite), Ajax (quartzite) and Sharon Creek (siliceous argillite) are restricted to the Trout Lake area. The Jowett is a mafic volcanic unit.
The Tonawanda prospect is underlain by grey and black phyllites of the middle member of the Boadview Formation. The rocks are near the axis of the Silver Cup anticline and are isloclinally folded and locally highly deformed. The area has a similar structural and stratigraphic setting to the Nettie L.[082KNW100] deposit to the southeast.
The two adits on the property are at approximately 1300 metres elevation in a small draw 90 metres south of Fissure Creek. In 1904, the main crosscut is reported to have been driven through barren grey to black grits and phyllites for 16.7 metres. It cut the "lead" and then drifted on it for a further 12.2 metres. At some point, a winze was sunk on the "ore shoot" for a depth of approximately 9.0 metres. In 1955, there was an unsuccessful attempt to reopen the adit and explore the vein underground. The following year, the then operators diamond drilled two short holes, from bedrock near the portal, and encountered a large mud seam that contained a little pyrite and a few specks of chalcopyrite. By 1962, the portal was once again obscured by debris; however it was relocated through its dump. Although there were reported to be sulpide-bearing fragments on the dump at the time of the abortive effort to reopen it in the 1950s, none were found in 1962. The debris consisted of abundant fragments of black phyllite containing a little quartz but little in the way of economically significant sulphide. There is also a second, shorter, adit that traverses barren grey grits for approximately 15 metres. In 1958, a jeep-road was built to this adit from the True Fissure road.
St. Patrick Mining prospected the area between 1992 and 1997 and located a gossan in crushed phyllite on the adjacent Revenue [082KNW007] claim. The Company conducted several soil sample programs looking for extensions of the True Fissure mineralized system on the property, with mixed results.
