The Weir Mountain occurrence is located 5 kilometres north of Mount Weir and 10 kilometres east of Surprise Lake, about 44 kilometres northeast of the community of Atlin.

The showing is based upon a tungsten occurrence shown on Map 1082A of Geological Survey of Canada Memoir 307. It is located in the middle of the Surprise Lake batholith (Surprise Lake Plutonic Suite) which covers about 1100 square kilometres east and northeast of Atlin. The batholith is dated at 70.6 plus or minus 3.8 million years or Late Cretaceous. It is composed primarily of medium grained, equigranular alaskite which is essentially a leucocratic granite with microcline and orthoclase with subordinate quartz and may or may not contain plagioclase and mafics. There are some coarse grained quartz feldspar porphyritic varieties. The contacts between the various textural varieties are commonly gradational. There are also some massive aplitic dikes which crosscut the batholith. There are very coarse grained pegmatitic zones within the alaskite with large quartz and feldspar crystals and books of biotite. The width of these zones varies considerably, but the contacts are almost always sharp.

Mineralization occurs as disseminated wolframite and molybdenite in quartz veins with minor malachite. Like the dikes, the veins vary in orientation from a northwest strike and southwest dip to a slightly more common northeast strike and northwest dip.

In 1969 and 1971, mapping, sampling and soil surveys were completed but no significant results were achieved. In 1979, Mattagami Lake Explorations investigated the showings. A sample of a 2-centimetre-wide quartz vein contained 0.008 per cent tungsten and 0.071 per cent molybdenum. Another sample contained 0.055 per cent tungsten and 0.023 per cent molybdenum (Assessment Report 8413, page 18).

In 2006, Aldershot Resources Ltd. conducted a spectral analysis program on their Atlin East property which covers the CX (104N 114), Mir 3 (104N 113), Mir 7 (104N 112) and CX 2 (104N 111) occurrences. The program involved acquisition of satellite spectral data available from NASA, reconfiguring the data into a workable format, geo-referencing to TRIM map bases and extensive and rigorous classification of the data in search of indicators that might lead to the discovery of uranium mineralization.