The Kleanza copper prospect (Croesus claims 1-130) covers Kleanza Mountain, about 12 kilometers north east of Terrace. Kleanza Mines Limited staked the initial Croesus group in 1965-66. During 1967-68, exploration work continued on the Croesus, Excelsior (103I 081), Gem (103I 136) and other properties.

Granodiorite of the Cretaceous to Tertiary Coast Plutonic Complex intrudes volcanic rocks of the Jurassic Hazelton Group. The Harlequin vein is a flat-lying, 1 metre wide quartz vein that dips 45 degrees to the north. It is located midway between the Black Bull former producer and the Excelsior showing ( Minfile103I 081). Sphalerite and galena occur along the hangingwall of the vein. A chip sample across the vein assayed 1.1 grams per tonne gold and 31.9 grams per tonne silver and a selected float sample assayed 0.3 grams per tonne gold, 143.3 grams per tonne silver, 6.90 per cent zinc and 22.50 per cent lead (Assessment Report 12072).

The Dollar vein, located 100 metres northeast of the Harlequin vein, is a 4 to 15 centimetre wide quartz vein which is sparsely mineralized with pyrite and traces of molybdenite. A selected sample from the vein assayed 0.205 grams per tonne gold (McClintock, 1987).

The Harlequin area was prospected and sampled by Decade Resources Ltd. during their 2019 exploration program. Although the Harlequin showing was not mentioned in the report, it is within the "Road Zone" consists of several small-scale outcrops mainly along the former principal logging road north-to-northwest of the Excelsior and south of the Lucky Boy (Black Bull) adits. Rock sampling results for the area, both historically and in 2019, show elevated values for Au, Ag, Cu and Mo (Assessment Report 38909).