The Brett (Anderson Lake Mine) occurrence is located west of Anderson Lake and north of McGillivray Creek.
The occurrence is hosted in metasediments consisting of argillite, slate, tuffs and minor limestone of the Mississippian to Jurassic Bridge River Complex (Group), which is intruded by granodiorite tongues and stocks of the Cretaceous to Tertiary Bendor pluton. Slates are schistose and fissured in all directions. The fissures are frequently quartz filled.
The deposit consists of an irregular, ribboned quartz-ankerite vein, averaging 4 to 7 metres in width, striking north and dipping steeply west and conformable to the black slates and interbedded carbonaceous phyllite. Visible gold is concentrated locally and is occasionally coarse. Pyrite is the main sulphide in the vein, with some intersections showing arsenopyrite, chalcopyrite, sphalerite and sparse galena. Alteration minerals include sericite, mariposite, calcite and ankerite.
Due to the characteristically high amount of coarse free gold in the ore, additional cuts of the same crushed sample gave assay results that varied widely. A 2.4-metre channel sample (Sample 1815) assayed four times gave: 1145 grams per tonne gold and 528 grams per tonne silver, 5.8 grams per tonne gold and trace silver, 293 grams per tonne gold and 65.14 grams per tonne silver and 2.06 grams per tonne gold and 3.42 grams per tonne silver (Minister of Mines Annual Report 1962, page 27).
In 1910, a sample from the No.2 drift is reported to have assayed 166.9 grams per tonne gold over 35 centimetres (Assessment Report 11749). Sampling of the No.3 drift, in 1933, is reported to have yielded 8.5 grams per tonne gold over an average width of 1.5 metres, from 112 samples (Assessment Report 11749). The following year, assay plans from the No.2 and 3 levels reported values up to 26.7 grams per tonne gold over 2.58 metres (Assessment Report 11749). In 1947, sampling of the Mac tunnel is reported to have yielded a weighted average of 7.2 grams per tonne gold across 1.8 metres and for a length of 15 metres (Assessment Report 11749).
In 1983, a 10-metre sample of footwall material from the No.3 adit assayed 0.82 grams per tonne gold (Assessment Report 11749). In 2005, a dump sample assayed 1.15 grams per tonne gold (Assessment Report 28240).
The mine was in production from 1900 to 1904, in 1910 and again in 1962. The total amount of ore extracted was 9177 tonnes, which yielded 21.4 kilograms of gold. The mine was worked on several levels but most of the production came from the "49er" level.
Following the discovery of gold in the Bridge River area in 1896, and during the subsequent gold rush of the 1930s, the Anderson Lake area saw extensive exploration. The Anderson Lake mine was originally staked in 1897. During 1900 through 1903, Anderson Lake Mining and Milling completed three drifts following a quartz vein 1.8 to 2.4 metres in width. The No.1 drift, at 990 metres in elevation, extended for 45 metres, while the No.2 drift, at an elevation of 1035 metres, was 150 metres long. The No.3 drift also extended for 45 metres. In 1947, Golden Contact Mines acquired the property and completed 328.5 metres of diamond drilling and 88.5 metres of drifting in the “Mac” tunnel, located 26.5 metres below the No.3 drift. The following year the “49er” adit, located at an elevation of 956 metres, was driven for a length of 114.6 metres. In 1949, a further 151 metres of drifting and 76.8 metres of crosscutting was completed on the “49er” adit, while another adit known as the “Pep” adit, located 81 metres below the “49er” adit, was started with 18 metres of crosscutting. During 1950 through 1953, 639 metres of drifting, raises and crosscutting was completed on the “Pep” adit. In 1961, the “Pep” and “49er” adits were re-opened and a raise was driven between the two adits.
In 1983, X-Cal Resources completed a program of rock and silt sampling and geological mapping on the area as the Mac and X-Cal claims. In 1984, Magnus Resources completed a ground magnetic and electromagnetic survey on the area. In 1985, Hudson Bay Exploration and Development completed a program of geochemical sampling, geological mapping and a ground electromagnetic survey. The following year, Magnus Resources completed a lone drill hole, totalling 36 metres. In 1989 and 1990, Teck completed programs of rock, silt and soil sampling, geological mapping and a ground electromagnetic survey on the area. In 1991, Cogema completed a program of geochemical sampling and geological mapping on the area. In 2005, a minor prospecting program was completed. In 2006 and 2007, the area immediately south west was prospected as the Lil Andy claims. In 2012, a minor program of soil sampling was completed.