The Cup Lake uranium deposit is located approximately 1 kilometre east of Lassie Lake and 8.7 kilometres northwest of the Kettle Valley community of Christian Valley. The deposit consists of 2 mineralized areas; the northern part contains higher grade reserves than the southern part, 2000 metres to the southeast.

Granite and porphyritic quartz monzonite of the Cretaceous-Tertiary Okanagan Batholith, and syenite and monzonite of the Eocene Coryell Intrusions underlie the deposit.

The Miocene-Pliocene Chilcotin Group occurs as isolated, flat- lying, cap rocks consisting of vesicular and massive columnar olivine basalt flows with occasional interformational sediments. A potassium/argon age of 5.0 plus or minus 0.50 Ma was determined for the basalt (Map 29). Miocene fluvial sediments underlying the basalts are unconsolidated, interbedded arkosic sandstones, siltstones, carbonaceous mudstones, and basal conglomerates. These sediments occur as structurally controlled 'paleochannels', which are host to uranium deposits.

The property was staked in 1971 for Nissho-Iwai Canada Ltd. following radiometric and water geochemical surveys. Work prior to the uranium moratorium in 1980 consisted of 1045 metres of diamond drilling in 16 holes in 1972, 1292 metres of diamond drilling in 1973, and geological mapping and 3149 metres of diamond drilling in 40 holes in 1979. This work was carried out for the Power Reactor and Nuclear Fuel Development Corporation of Japan.

The CUP LAKE deposit occurs within a northwest trending paleochannel overlying Valhalla, Nelson, and Coryell intrusives. The fluvial sediments, up to 20 metres thick, include ash fall tuff with occasional lacustrine-type sediments overlying conglomerates. These are capped by a 5000 by 800 metre area of basalt, up to 60 metres thick.

The northern part of the mineralized zone measures about 1500 by 500 metres with an average grade of 0.042 per cent uranium over an average thickness of 1.8 metres; the southern part measures about 1500 by 150 metres with an average grade of 0.024 per cent over a 0.7 metre thickness (Assessment Report 8105). Total drill indicated reserves are estimated to be 2.25 million tonnes grading 0.037 per cent uranium to yield 839,620 kilograms of uranium (Assessment Report 8105).

Secondary uranium mineralization, which is probably saleeite and autunite, occurs as films on pebbles and in the matrix of unconsolidated or loosely consolidated conglomerate, carbonaceous mudstone, and sandstone. Mineralization is also in the base of the overlying basalt and in the regolith of the basement rocks.