The Lucky Jem polymetallic vein prospect is located at the headwaters of Eldorado Creek, 4 kilometers southwest of Eldorado Mountain. The prospect is mostly within or adjacent to dykes and apophyses of quartz diorite, granite and granodiorite, related to the Eldorado pluton of Paleocene age. Mineralization also occurs in country rocks of siltstone, sandstone, mudstone and arkose of the Upper Triassic Hurley Formation, Cadwallader Group. The sedimentary rocks are partly schistose. Stringers of arsenopyrite and pyrite are within decomposed and oxidized igneous and sedimentary host rocks; this material, when panned, will yield fine gold.

The prospect has been explored by two adits. The No. 1 adit vein, in a well defined fissure in granite, strikes northwest for 11 metres, dipping shallowly east. A wide (30 to 90 centimetres) oxidized zone carries arsenopyrite streaks surrounded by several centimetres of talcose gouge grading into decomposed granite. Assays ran from 34.28 grams per tonne gold and 17.1 grams per tonne silver over 50 centimetres to 0.68 grams per tonne gold and 34.28 grams per tonne silver over 50 to 90 centimetres (George Cross News Letter No.202, 1983). Sixty-five metres west of the No. 1 adit vein another drift, the No. 2 adit, follows two 30 to 60 centimetre subparallel, north striking veins through decomposed granite. The veins carry arsenopyrite and pyrite mixed with quartz and oxidation products. Assays across 127 centimetres at the junction of two veins graded up to 1.37 grams per tonne gold and 48 grams per tonne silver (George Cross News Letter No.202, 1983). A best assay of 43.88 grams per tonne gold and 89.14 grams per tonne silver is reported from an open cut southwest of No. 2 adit (Assessment Report 9062).