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 and other properties.

Andesite of the Jurassic Hazelton Group is intruded by quartz diorites, quartz monzonites, and hybrid rocks of the Cretaceous to Tertiary Coast Plutonic Complex. The main showing is a quartz-pyrite vein with minor chalcopyrite. The vein, which strikes 010 to 026 degrees and dips 60 to 72 degrees east, follows a fault zone near the contact between the volcanics and intrusives. The vein ranges from 15 to 50 centimetres in width, and is exposed intermittently along the strike length for 300 metres and about 120 metres downdip.

Adits 1 and 2 intersect the best mineralization. In adit 1, an ore-shoot measured 40 metres long and averaged 40 centimetres wide. A 30 centimetre sample assayed 14 grams per tonne gold and 7 grams per tonne silver (Geology, Exploration and Mining in British Columbia, 1971). In 1988, a chip sample from a vein in drift #2 assayed trace to 105.9 grams per tonne gold (Assessment Report 17260).

Laboratory tests indicate the gold and silver are present as tellurides which occur as tiny inclusions and fillings in spongy pyrite. Minor scheelite, galena, sphalerite and tetrahedrite has also been reported.

In 1940, about 2 tonnes of ore was shipped from the Black Bull Group (includes the Gem and Blue Bird claims). This ore shipment produced 31 grams of gold and 62 grams of silver.

Reserves of about 4355 tonnes averaging 26.06 grams per tonne gold and 59.31 grams per tonne silver were calculated over a length of 34 metres and a width of 0.4 metres for the Gem vein (Sharp, 1971).

Erickson Gold Miing drilled (20 holes, 1917 metres) the property in 1988.

Decade Resources Ltd. re-sampled the area of the Black Bull (Lucky Boy, Gem) adits and dumps as part of their Terrace Gold property exploration program in 2019. The results indicate that the vein system is characterized by highly variable (locally very high) gold and silver values. Importantly, it appears that the Lucky Boy vein is accompanied by a sub-parallel vein/mineralized system some 100 metres westward (in footwall) of the main system. This additional vein/zone is characterized by a common presence of chalcopyrite and strongly elevated concentrations of copper, besides gold and silver (Assessment Report 38909).