The Twin 3 occurrence is located at an elevation of approximately 1360 metres, west of the central arm of Homestake Creek and approximately 3.5 kilometres southwest of Samatosum Mountain.
The area is underlain by four thrust-bounded sub-assemblages of the Early Cambrian to Late Mississippian Eagle Bay Formation: the Rea, Plateau, Homestake and Acacia assemblages. The Rea assemblage, which underlies the immediate area of the Twin occurrence, consists of a structurally inverted sequence of mafic pyroclastics and flows containing Tshinakin limestone. The mafic series is stratigraphically overlain and structurally underlain by a thick sequence of clastic sediments. The Rea zone, a 10 to 150-metre-thick section of stratigraphy at the mafic volcanic-sediment contact, hosts the Rea Gold (MINFILE 082M 191), K-7 (MINFILE 082M 277) and Twin occurrences. The Plateau assemblage lies to the southwest and consists of mafic, intermediate and felsic volcanics with lesser interbedded argillite. Structurally underlying the Plateau assemblage is the Homestake assemblage, which consists of five distinct units consisting of calcareous sediments, mafic volcanics, sericite schists, interlayered sericite schist, phyllite, chert and argillite and unaltered felsic volcanics. Further south, well-bedded and complexly folded quartzites, quartz wackes, siltstones and argillites comprise the Acacia assemblage.
Three distinct northwest-trending units are exposed on the Twin property. In order from oldest to youngest, these units are the following: a thick, well-foliated, homogeneous pile of mafic flows and pyroclastic rocks known as the footwall mafic volcanics; altered felsic volcanics, cherts and pyritic sediments that host Rea and Silver zone massive sulphide mineralization; and a package of turbidites, coarse wackes, conglomerates and intermediate to mafic volcanics. Contacts between the units strike between 135 and 156 degrees and dip between 45 and 60 degrees to the northeast. An isoclinal anticline has folded the mineralized horizon.
The Rea and Silver mineralized zones trend from northwest to southeast. In this area, the Rea zone is a continuous, well-defined stratigraphic horizon that hosts several massive sulphide lenses (such as the Rea Gold [MINFILE 082M 191]). The 1991 drill program encountered chloritic mafic volcanics containing massive sulphide veins up to 30 centimetres in width. Pyritic stockwork mineralization was also encountered within felsic volcanics. A second mineralized stratigraphic horizon, the Silver zone, parallels the Rea zone to the northeast. This zone hosts the Samatsum deposit (MINFILE 082M 244). The Silver zone consists of 50 metres of interbedded graphitic argillite and siltstone, sericitic cher and pyritic sediments. The pyritic sediments range from fine siltstone to coarse chert pebble conglomerates. Chert pebble conglomerates with interbedded wacke contain 30 to 40 per cent pyrite occurring as both very fine grained matrix and recrystallized granoblasts. Traces of blebby sphalerite, galena and chalcopyrite also occur. This zone remains open along strike and downdip.
In 1981, a sample from the West Trench area of the Twin Mountain (MINFILE 082M 020) mineralized trend, located immediately east of the Twin 3 claim and on the east side of Homestake Creek, yielded 2.61 per cent copper, 0.04 per cent lead, 2.87 per cent zinc, 7.5 grams per tonne silver and 0.21 gram per tonne gold (Assessment Report 9882).
In 1985, a drillhole (AA-2), located approximately 600 metres to the east of the main Twin 3 zone, intersected a mineralized chert and tuffaceous argillite yielding up to 0.37 per cent zinc, 0.25 per cent lead, 6.4 grams per tonne silver and 0.4 gram per tonne gold over 0.9 metre (Property File - Falconbridge Copper Corp. [1985-02-17]: Drill Hole Records and Assay Results - Twin 2-3 claims).
In 1987, Apex reported a 1.83-metre drill interval (Hole Twin 3 on the Rea Zone) that assayed 30.86 grams per tonne gold, 250.29 grams per tonne silver, 0.77 per cent zinc, 2.1 per cent lead and 0.24 per cent copper (George Cross Newsletter, No. 237, December 10, 1987). A 4.1-metre drill interval from the Twin property was reported to have yielded 12.8 grams per tonne gold, 108 grams per tonne silver, 0.2 per cent copper, 1.5 per cent lead and 0.6 per cent zinc (Assessment Report 22389, page 1). It is possible that the former assay was a sub-interval of the latter.
Other drilling intercepts included 0.23 gram per tonne gold, 10.1 grams per tonne silver, 0.07 per cent copper, 1.20 per cent lead and 1.17 per cent zinc over 0.8 metre in the nearby hole Twin 4 and 2.32 grams per tonne gold, 47.6 grams per tonne silver, 0.04 per cent copper, 0.22 per cent lead and 0.16 per cent zinc over 0.40 metre in hole Twin 2, located approximately 300 metres north-northwest of the previous holes (Assessment Report 16774). These holes also tested the Rae zone trend. Later that year, another drillhole (Twin 9), located a short distance north of holes 3 and 4, yielded 8.79 grams per tonne gold, 277.3 grams per tonne silver, 2.74 per cent lead, 3.13 per cent zinc and 0.55 per cent copper over 2.4 metres (Property File - Esso Minerals Canada [1987-09-08]: Progress Report - August 1987 - Twin Property - Adams Lake area).
In 1990, drilling is reported to have intersected the Rea horizon stratigraphy down to 300 metres below surface and two have intercepted a new zone (Silver zone?) of mineralization in the deepest holes, yielding up to 2.85 grams per tonne gold, 11.8 grams per tonne silver, 0.44 per cent lead and 0.85 per cent zinc over 4.5 metres (523.5 to 528.0 metres downhole) in hole T90031 (Property File - Apex Energy Corp. [1990-12-18]: No. 244 (1990) - Twin Property Drill Results). The mineralization is reported to be open at depth.
In 1991, drilling on the Twin 3 occurrence area yielded intercepts including 0.222 and 0.807 gram per tonne gold, 12 and 13 grams per tonne silver, 0.035 and 0.062 per cent copper and 0.113 and 0.191 per cent lead with 0.186 and 0.335 per cent zinc over 21.8 and 7.6 metres (263.1 to 284.9 and 296.6 to 304.2 metres downhole), respectively , including 9.46 grams per tonne gold, 89.8 grams per tonne silver, 0.342 per cent copper, 3.63 per cent lead and 5.66 per cent zinc over 0.20 metre in hole T91036 from the Silver zone horizon (Assessment Report 22389). Also at this time, drillhole T91037 intercepted the Silver and Rae horizons, yielding up to 1.09 and 0.07 grams per tonne gold, 3.9 and 7.9 grams per tonne silver, 0.113 and 0.675 per cent copper and 0.203 and 2.72 per cent lead with 1.02 and 2.94 per cent zinc over 0.5 and 0.4 metre (237.7 to 238.2 metres and 576.8 to 57.2 metres downhole), respectively (Assessment Report 22389). Drillholes T91036 and T91037 were located approximately 400 metres north and 150 metres northeast, respectively, of the 1987 drillholes.
In 2000, a float sample (104721) with semi-massive sulphides from the Twin 3 lens area assayed 0.42 gram per tonne gold, 3.4 grams per tonne silver, 0.070 per cent copper, 0.089 per cent lead and 0.092 per cent zinc (Assessment Report 26595).
In 2004, a chip sample from a newly discovered quartz carbonate veined outcrop reported to be related to the Twin Mountain horizon zone, located approximately 750 metres to the north-northeast of the Twin 3 occurrence and at an elevation of approximately 1460 metres, assayed 0.06 gram per tonne gold, 8.2 grams per tonne silver, 1.144 per cent lead and 0.445 per cent zinc over 1.0 metre (Assessment Report 28208).
Exploration in the area began in the late 1800s. To the southwest, exploration for copper, lead, zinc, gold, silver and barite began at the Homestake mine (MINFILE 082M 025) in 1893. Limited production took place from 1926 to 1927, 1935 to 1936 and 1983 to 1984. To the east, the Twin Mountain zone has been explored intermittently since 1936. Exploration focused on massive copper, lead, zinc and barite sulphides.
Mineral exploration on the Twin property began in the 1930s. The Twin Mountain occurrence (MINFILE 082M 020), situated approximately 1.5 kilometres to the southeast, is a silver-lead-zinc–bearing quartz-dolomite vein discovered in 1936 and explored sporadically by several operators.
The Twin claims were staked in 1980. In 1983, Lincoln Resources Incorporated entered into an option agreement with Apex Energy Corp to work on the Twin property. A grid was established and a soil survey was carried out.
Falconbridge Copper acquired the property from Lincoln Resources in 1984 and conducted mapping, rock sampling, Max-Min II and very low-frequency electromagnetic (VLF-EM) geophysical surveys. In early 1985, Falconbridge Copper proposed a nine-hole, 2400-metre drill program to test targets on the Rea Gold (MINFILE 082M 191), Austin-Apex and Kamad (MINFILE 082M 277) options. Three drillholes totalling 350 metres were planned for the Austin-Apex property. Only two of the nine diamond drill holes were completed, neither of which intersected the target horizon. In spring 1985, Falconbridge Copper dropped the option on the property and returned it to Lincoln Resources.
Later that year, Lincoln Resources conducted a limited fill-in soil survey. In 1986, Lincoln Resources and Apex Energy hired J.D. Blanchflower to undertake an exploration program on the Twin property. As part of the 1986 program, the 1983 grid was re-established and extended and further rock and soil sampling and mapping was conducted. Genie electromagnetic surveying and trenching were also completed on the Rea zone.
In late 1986, Esso Minerals Canada optioned the property from Lincoln Resources and Apex Energy. Early in 1987, Esso Minerals conducted a very low-frequency electromagnetic geophysical survey over geochemical target areas. This was followed by 2269 metres of diamond drilling, which resulted in the discovery of a small, gold-rich massive sulphide–barite lens on the Twin 3 claim. During the summer of 1988, Esso Minerals drilled 1278 metres in eight holes and performed additional geophysics and geological mapping targeting the Rea and Twin Mountain zones.
Homestake Canada Limited acquired Esso's option in 1989 and performed a limited amount of trenching on the Twin Mountain zone. In 1990, Homestake completed 4017 metres of NQ diamond drilling in nine holes and 2235 metres of down-hole pulse electromagnetic geophysical surveying in six of the holes. Homestake conducted a further 4069 metres of diamond drilling in six holes in 1991. Four of the Twin drillholes intersected Silver zone mineralization.
In 2000, Paul Watt staked the Extra High property on the area immediately south and west of the occurrence . From late 2000 through 2003, Watt completed programs of prospecting, geochemical (rock and soil) sampling and geological mapping.
In 2004, Brinx Ventures Inc. acquired the Extra High property and completed a program of trenching and 18 diamond drill holes, totalling 1874.3 metres, on the property the following year.