The O/C 3 occurrence is located on a logging road on the east side of Vanstone (Horseshoe) Creek at 925 metres elevation. The showing lies 600 metres northeast of the O/C 1-2 occurrences (092F 681), approximately 18 kilometres north-northeast of the town of Gold River.

The majority of the area is underlain by grey-green weathering, quartz-calcite amygdaloidal basalt of the Upper Triassic Karmutsen Formation. The basalt sequence is cut by five distinct intrusive suites, which include: lamprophyre dykes; medium-grained, equigranular granodiorite dykes; strongly feldspar-hornblende porphyritic dykes of intermediate composition; a fresh, hornblende granodiorite stock of likely Early Cretaceous age; and a small, poorly exposed stock, or dyke, of dioritic composition near the north-west corner of the property. Silicification, chloritization and epidotization are observed.

At the O/C 3 occurrence, a grab sample of a 0.5-centimetre pyrite vein in andesite near a small north-east striking, near vertical fault returned values of 1.4 grams per tonne Au (Assessment Report 38287).

At the O/C 2 occurrence several feldspar-hornblende and granodiorite dikes cut strongly fractured and biotite-altered volcanic rocks over a length of 350 metres. Mineralization consists of 10 to 15 per cent pyrite, with minor chalcopyrite and molybdenite occurring as disseminations and fracture coatings. In 1995, 65 chip samples, taken over 3 metre widths, yielded an average of 0.022 per cent copper, 0.0256 gram per tonne gold and 0.0005 per cent molybdenum (Assessment Report 24178).

In 1969 and 1972, Moresby Mines completed programs of geological mapping and rock and soil sampling on the area known as the Vanhall claims. In 1980 and 1981, Eastern Leaseholds completed programs of soil sampling and airborne electromagnetic and magnetic surveys. During 1994 through 1997, Cominco completed programs of geological mapping, geochemical sampling and ground magnetic and electromagnetic surveys on the area known as the Chum claims. In 2011, Universal Ventures Inc. completed a program of geochemical sampling, geological mapping and an airborne geophysical survey on the area known as the Tib claims, Tibor property.

In 2017 and 2018 an interpretive study followed by limited rock sampling was conducted in the Vanstone Creek area by tenure holder K. Galambos (Assessment Reports 37381, 38287). The O/C 3 showing was discovered during rock sampling in 2018.