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 (130I 081), Gem (103I 136) and other properties.

The area is underlain by plutonic rocks of the Cretaceous to Tertiary Coast Plutonic Complex. The oldest rocks include coarse pegmatite and related quartz feldspar porphyry, which grades to quartz diorite porphyry. These rocks are intruded by quartz monzo- nite and a related igneous breccia. All the rocks are intruded by an east-striking, 5 metre wide quartz porphyry dyke.

Pyrite, chalcopyrite and locally, bornite and molybdenite, occur as fracture fillings and disseminations. Stockworks of quartz veinlets with selvages of sulphides are also present within leucocratic to pegmatitic phases of the intrusive. Alteration accompanying the mineralization includes sericitization, kaolinization and chloritization.

Trenching has exposed low grade, porphyry-style mineralization over a 400 metre by 200 metre area. A grab sample from one trench assayed 1.7 grams per tonne gold, 15.4 grams per tonne silver and 0.2 per cent copper (Assessment Report 12072). Scheelite has also been reported in the area.

Decade Resources Ltd. re-sampled the area of the White Bluffs showing as part of their Terrace Gold property exploration program in 2019, referring to it as the Croesus Porphyry. Sampling results for this area showed relatively low values of copper and other element concentrations, however only a small area was explored (Assessment Report 38909).