The area is underlain by a fault-bound block of Permian to Jurassic Hozameen Complex rocks consisting mainly of shale/argillite. This is in contact to the north and east, as shown by Muller (GSC Map 41-1989), with metamorphic rocks of the Custer Gniess and to the west with Eocene conglomerate. The country rocks have been intruded by the Cretaceous Spuzzum pluton, the contact of which is just a few kilometres to the west, and a nearby granodioritic mass related to an unnamed early Tertiary pluton which occurs across the Fraser River to the southeast.

The Ideal Gold occurrence appears to be located in the area mapped as Custer Gneiss. These rocks are believed to have been derived from lower Mesozoic and possibly Paleozoic rocks and metamorphosed in the Cretaceous. The Minister of Mines Annual Report 1934 describes the rocks near the main adit as hornblende diorite in contact with altered siliceous feldspar tongues and dikes. The Minister of Mines Annual Report 1966 describes the rock in the adit as granite or granodiorite, crushed and strongly silicified, containing many dark bands and lenses, some of which are lamprophyre, and some of which appear to be argillite or pyroxene and amphibole.

In 1934, it was reported that two bodies of quartz were intersected in the 155-metre adit, the first at 58 to 67 metres from the portal, and the second at 101 metres from the portal. Six 1.5-metre samples were taken across the first showing but all samples yielded only traces of gold and silver (values of 8 to 14 dollars per ton were reported in 1934) (Minister of Mines Annual Report 1934, page F19). The second exposure at 101 metres also yielded only a trace of gold and silver across 0.9 metre. An opencut in talc shcist, about 100 metres in elevation above the adit, exposes an 86- centimetre wide lens of quartz. A sample across this yielded traces of gold and silver (Annual Report 1934). In 1966, the adit was reported to be 274 metres in length.