The B.C. Vein is located on the low slopes southwest of Barkerville Mountain, near the divide between Lowhee Creek and Stouts Gulch, about 2.4 kilometres west-southwest of Barkerville.

The B.C. Vein occupies a structure referred to as the B.C. fault (Assessment Report 26604); it strikes northwest, dips moderately to steeply northeast, and has been traced in outcrop and drilling for about 1200 metres (Press Release - International Wayside Gold Mines Limited, June 18, 2002). It is hosted in dark grey phyllites, metasiltstones and quartzites of the Upper Proterozoic-Paleozoic Snowshoe Group. The vein ranges up to 20 metres in thickness, but is locally thin to absent and marked by carbonaceous gouge seams containing fragments of quartz defining the B.C. fault. Although it consists of a single vein over much of its strike length, the B.C. Vein locally splits, commonly into a master vein with multiple splays and parallel veins in the footwall. The vein material is composed mainly of white quartz, locally with minor amounts of iron carbonate (siderite). The quartz is massive to ribboned or brecciated. Ribboned sections contain carbonaceous, often stylolitic partings, and wallrock slivers.

Much of the vein is sulphide-poor quartz that does not contain significant gold values. Significant gold mineralization is found mainly northwest of the B.C. shaft, and is associated with coarse-grained pyrite, with accessory galena, chalcopyrite, sphalerite and cosalite (Assessment Report 26604). The most significant intersection reported from the 1998-2002 drilling by International Wayside was 15.8 metres grading 22.97 grams per tonne gold in diamond-drill hole BC02-03 (Press Release - International Wayside Gold Mines Limited, June 18, 2002).

The considerable strike length and thickness of the vein, together with its location near the headwaters of two major placer gold-producing creeks, attracted some of the earliest lode gold exploration in the area, including some underground development in the late 1870s and 1880s (Minister of Mines Annual Report 1897). In 1941, the 1500-level crosscut of the Cariboo Gold Quartz mine (093H 019) was extended 1.5 kilometres southeastward to intersect the B.C. Vein, and a previously developed inclined shaft on the vein was deepened to intersect the crossscut extension. The deepening of the shaft yielded 824 tonnes of development muck grading 6.17 grams per tonne gold. The underground development intersected several areas of mineralization in the vein, some of which was subsequently mined to yield 3804 tonnes grading 17.14 grams per tonne gold. Surface exposures of the vein were stripped in 1947, and several well-mineralized areas identified. The best of these zones were subsequently developed by surface pitting and limited stoping, yielding 1846 tonnes grading 38.74 grams per tonne gold in 1948-49 (Assessment Report 26604). Production is probably included in Cariboo Gold Quartz (093H 019). There was little further development work on the vein prior to extensive drilling by International Wayside Gold Mines Limited beginning in 1998. This drilling defined additional mineralized zones in the B.C. Vein and also led to the discovery of the Bonanza Ledge occurrence (093H 140), in the footwall of the B.C. Vein, in March 2000.

A 2002 resource estimate by Giroux Consultants Ltd. of Vancouver shows indicated resources of 295,747 tonnes grading 5.314 grams per tonne gold in the B.C. Vein, using a 0.686 gram per tonne gold cutoff. Inferred resources, using the same cutoff, are 291,211 tonnes grading 2.4 grams per tonne gold (Press Release - International Wayside Gold Mines Limited, December 3, 2002). In 2002, International Wayside began a scoping study to evaluate the possibility of open-pit mining the B.C. Vein, Bonanza Ledge and Cariboo Gold Quartz resources utilizing a central milling facility.

In 2009, International Wayside Gold Mines Ltd. received results from the first phase of its infill diamond drill program in the Bonanza Ledge zone (093H 140) on Barkerville Mountain and from three diamond-drill holes testing the mine grid west extension of the BC Vein (this description) on Cow Mountain.

Drillholes CM09-01 through CM09-03 were completed beside Lowhee Creek on Cow Mountain and confirm the mine grid west extension of the BC Vein. The results verify that strike quartz veins including BC Vein exist on Cow Mountain, though more drilling needs to be conducted to confirm the total length and depth along strike. Gold values returned from the strike veins are up to 20.5 grams per tonne (drillhole CM09-02) (Press Release - International Wayside Gold Mine Limited, September 17, 2009).

The potential gold resource of the BC Vein has been significantly increased as it is now confirmed to extend approximately 1600 metres from Barkerville Mountain to Cow Mountain. Drillhole CM09-01 also confirms the existence of volcanic rocks and conglomerate in the Lowhee Unit on Cow Mountain.

In 2016, the BC Vein was reported to have a strike length of 1400 metres and has been drilled to a depth of 400 metres below surface (Information Circular 2017-1, page 122).

In June 2018, an updated mineral resource estimate for the combined Bonanza Ledge, BC Vein, Mosquito, Shaft, Valley and Cow deposits was reported at 8,109,900 tonnes measured and indicated grading 6.1 grams per tonne gold and 12,731,200 tonnes inferred grading 5.2 grams per tonne gold (Beausoleil, C. (2018-06-14): NI 43-101 Technical Report and Mineral Resource Estimate Update for the Cariboo Gold Project).

In 2018, Barkerville Gold Mines Ltd. completed a program geological mapping, channel, rock, soil and underground sampling and 449 diamond drill holes, totalling 128,759 metres, on the Cariboo Gold property.

In late May 2019, an updated mineral resource estimate for the combined Bonanza Ledge, BC Vein, Mosquito, Shaft, Valley and Cow deposits was reported at 13.495 million tonnes measured and indicated grading 5.6 grams per tonne gold with an additional 11.936 million tonnes inferred grading 5.0 grams per tonne gold, using a 3.0 grams per tonne gold cut-off grade (Beausoleil, C. (2019-07-11): NI 43-101 Technical Report and Mineral Resource Estimate Update for the Cariboo Gold Project).

In 2019, Barkerville Gold Mines Ltd. completed a program of geological mapping and 109 diamond drillholes, totalling 45,641 metres, on the Cariboo Gold property. Drilling highlights included 21.91 grams per tonne gold over 7.85 metres true width in hole BCVN-19-015, while drilling on the Lowhee zone yielded up to 20.66 grams per tonne gold over 12.80 metres, including 352.00 grams per tonne gold over 0.65 metre in hole BM-19-105 (Morgan, G.J. (2019-09-17): NI 43-101 Technical Report - Preliminary Economic Assessment of the Cariboo Gold Project).

In April 2020, an updated resource was reported for the Cariboo Gold project (Bonanza Ledge [MINFILE 093H 140], BC Vein [MINFILE 093H 139], KL [MINFILE 093H 140], Lowhee [MINFILE 093H 139], Mosquito [MINFILE 093H 010], Shaft [MINFILE 093H 006], Valley [MINFILE 093H 019] and Cow [MINFILE 093H 019] deposits) with a total of 21 441 000 tonnes measured and indicated grading 4.6 grams per tonne gold with an additional 21 649 000 tonnes inferred grading 3.9 grams per tonne gold using a 2.1 grams per tonne gold cut-off grade (Beausoleil, C., Pelletier, C. [2020-10-05]: NI 43-101 Technical Report and Mineral Resource Estimate for the Cariboo Gold Project, British Columbia, Canada).

In 2020, Barkerville Gold Mines Ltd. completed 82 diamond drill holes, totalling 25 397.7 metres, on the Cariboo Gold project. Drilling on the B.C. Vein zone comprised three drillholes, totalling 560.6 metres, whereas drilling on the Lowhee zone comprised 24 drillholes, totalling 10 144.5 metres.