The Bren occurrence is located south of Horsefly Mountain at an elevation of approximately 1200 metres, on the north side of the Horsefly River Valley between Club Creek and the east fork of Black Creek.

Regionally, the area lies near the eastern margin of the Upper Triassic Nicola Group marine sedimentary and volcanic assemblage. The lowermost volcanic rocks consist of alkali basalt and alkali olivine basalt that, in this area, have been intruded by quartz porphyry dikes. These have been intruded by bodies of Late Triassic to Early Jurassic dioritic to syenitic rocks.

Locally, a thick sequence of northwest-striking, southwest-dipping mafic volcanic tuffs and flows(?) with intercalated argillites have been intruded by multiple apophyses of intrusions consisting of (biotite-quartz, feldspar-biotite and quartz-feldspar-biotite) monzonite, syenite, pyroxenite and porphyry and aplite dikes with local contact metasomatic zones. The contact zones are silicified and sericitized with minor epidote, chlorite and biotite and contain widely spaced, generally narrow but up to 2-metre wide, quartz-calcite veins with disseminations and veins of pyrite, pyrrhotite, arsenopyrite, chalcopyrite and sphalerite. Gold mineralization is associated with massive sulphide, primarily arsenopyrite, veins up to 40 centimetres wide. Semi-massive pyrite mineralization with minor chalcopyrite is present for greater than 2 metres in a heavily sheared zone adjacent to some of the quartz veins. Mineralized veins have been identified, intermittently, over an area of 250 metres east-west and 100 metres north-south.

Diamond drilling has identified widespread molybdenite mineralization as fracture coatings and disseminations in all units cored and related to an argillic-pyritic alteration zone beneath a silica capping characterized by a pyrrhotite-chalcopyrite-actinolite stockworks. An area or layer of ferricrete is also reported capping and/or associated with the mineralized zone. Drilling and trenching indicate a possible metal zoning of a copper-molybdenum-tungsten mineralized core with an outer halo of gold-associated arsenopyrite mineralization and peripheral fringe of lead-zinc-silver mineralization.

In 1983, rock samples of narrow mineralized veins exposed by an area of trenching yielded up to 14.9 grams per tonne silver, greater than 10.0 grams per tonne gold and 1.00 per cent zinc (Assessment Report 12363).

In 1995, a sample of mineralized ferricrete exposed by a new roadcut is reported to have assayed 1 per cent molybdenum, 0.30 per cent copper, 0.08 per cent tungsten and 0.44 gram per tonne gold (Assessment Report 25734).

In 1996, a grab sample (BF-96-07) of mineralized vein material from a past trench assayed 32.8 grams per tonne gold, 55.4 grams per tonne silver and 4.6 per cent zinc, whereas a 5.0-metre chip sample (BF-96-06) from the trenched area assayed 1.06 grams per tonne gold (Assessment Report 24717). Also, at this time chip sampling of new trenches (TR96-01), west of the past trenches, yielded 0.11 gram per tonne gold over 20 metres (Assessment Report 24717).

In 2000, diamond drilling intersected a molybdenum-bearing porphyry system yielding 0.021 per cent molybdenum over 59 metres in hole K-2 and 0.032 per cent molybdenum over 87 metres in hole K-3 (Assessment Report 26317).

In 2008, resampling of two quartz-molybdenite mineralized sections of drillcore from hole K-3 yielded values of 0.077 and greater than 0.200 per cent molybdenum with 121 and 943 parts per billion rhenium, respectively (Assessment Report 30356).

In 2012, sampling of trenches from the silica cap zone yielded up to 0.37 gram per tonne gold with elevated values of copper and molybdenum, whereas trenching on an 80-metre long oxidized saprolitic gossan zone, in excess of 8 metres deep and located along a granodiorite-silica cap contact, yielded up to 0.311 per cent copper, 0.014 per cent molybdenum, 22 grams per tonne silver and 0.83 gram per tonne gold (Assessment Report 33259). Also, at this time, a sample (K190655) from the former ‘Bren’ (Glory Hole) trenches of gold-bearing arsenopyrite mineralization assayed 16.6 grams per tonne gold, 16 grams per tonne silver and 0.163 per cent zinc (Assessment Report 33259).

In 1973, the first documented activity refers to the gold-bearing sulphide veins, which were probably discovered by logging operations of the time. The prospect was subjected to trenching (457 metres), soil sampling (22 line-kilometres) and magnetic surveying (14 line-kilometres).

In 1982, geochemical sampling indicated the presence of anomalous gold associated with sulphide mineralization. In 1983, the property was restaked by Selco (BP Exploration Canada Ltd.) as the HR 1-5 claims and 17.7 kilometres of grid work was completed consisting of soil sampling at 200-metre intervals and rock chip sampling of the old Bren trenches. In 1990, Noranda Explorations soil sampled the area immediately west as the Tacoma claim.

In 1995, the area was staked as the Keno claims by owners H. Wahl and J. Brown-John based on the discovery of high-grade ‘mineral’ occurring within ferricrete exposed by new road building. In 1996, the claims were optioned to Westmin, who completed a trenching program that failed to penetrate the ferricrete zone; the claims were subsequently returned. In 1997 and 1998, the owners completed 1 kilometre of induced polarization surveying across the existing zone and conducted prospecting with soil and rock sampling. In 2000, the owner-operators completed four drillholes, totalling 603.5 metres; two holes intersected molybdenite mineralization and bottomed in mineralization at 127 metres.

In 2006, the owner-operators conducted line cutting and a soil geochemical and geological reconnaissance survey focused on outlying areas from the molybdenum zone. In 2008 and 2011, further programs of soil sampling and prospecting were completed on the Keno claim. Also, during 2010 through 2012, Bullion Gold Corp. completed programs of soil sampling, 45.5 line-kilometres of induced polarization surveying and 1874.0 line-kilometres of airborne geophysical surveying on the surrounding area as a part of the Cariboo Goldfields and Horsefly properties.

In 2013, Woodjam Horsefly Resources Ltd. completed a program of soil and rock sampling and 1073 metres of trenching on the Keno claim. In 2016 and 2018, further programs of geochemical sampling and geological mapping were completed.