The Rex-Peso silver and gold zone lies approximately 4 kilometres west of the Eagle Gold Deposit, and is a southwestern extension of the Potato Hills mineralized belt. Historical work since the 1940s focused exploration on several silver-lead-antimony veins with an east-west strike. The vein system at Rex-Peso was extensively explored by Peso Silver Mines Ltd from 1961 to 1965, including underground development on the Peso No 1 vein and the Rex vein amounting to approximately 1,067 metres of drifting, shafting, and adits to approximately 90 metres below surface. Rock sample results indicated a 9m width of oxidised vein at Peso with 2.4m grading 0.06 oz/ton Au and 61.7 oz/ton silver. Five additional veins were outlined from 30-2800m strike lengths. Work on the Rex-Peso area was intermittent after 1964 and included small campaigns of surface trenching, limited drilling, and geochemical exploration.
From September to November, 2011, a first phase reconnaissance exploratory program of 12 diamond drill holes was completed for a total of 1,428 meters, targeted on vein systems which have remained essentially unexplored since the 1960s. The 2011 diamond drilling program confirmed the presence of thick, high-grade silver intervals, with best results of 4.81 m of 259 g/t Ag and 0.93 m of 0.45 g/t Au and > 10,000 g/t Ag. These high sulfide and quartz breccia veins have a very similar mineralogical signature and geological setting to those in the Keno silver district, 30 kilometres to the east-southeast, except in this case they are hosted in Proterozoic-Cambrian Hyland Group quartzite, schist and phyllite. Minerals in the sulfide veins include silver-rich galena, sphalerite, jamesonite and other sulfosalts.
Also of significant interest at Rex-Peso is the gold mineralization potential proximal to Cretaceous age intrusive dykes as well as carried in the silver vein-faults. Several operating current and past placer gold producers (e.g. Secret Creek) have their headwaters in the Rex-Peso area, and stream sediment samples returned anomalous gold throughout Secret Creek, Gil Gulch and 15 Pup. A series of outcropping dykes are observed in the area, however airborne geophysics suggests the presence of a much larger buried intrusion which may be feeding the system.
The 2017 exploration program consisted of a 50m x 50m spaced soil grid over the main Rex intrusion followed by a ground IP, Mag and VLF survey. 19 diamond drill holes for 3,300m and 23 trenches for 1,514m were subsequently completed over the Rex ridge area following up anomalous gold and arsenic in soil results as well as historically traced faults.