The Mir 3 occurrence is located just west of Terrahina Creek, about 49 kilometres east of the community of Atlin.

The area is underlain by alaskitic quartz monzonite of the Late Cretaceous Surprise Lake batholith (Surprise Lake Plutonic Suite). The rocks are commonly interlayered with aplitic and pegmatitic phases. To the east, the "Trout Lake graben", a northerly trending feature, brings roof rocks to the valley bottom.

A test pit on the Radon Cirque area uncovered galena, sphalerite, and minor chalcopyrite in veins within alaskite. Also associated with the sulphides are magnetite, hematite, pyrargyrite, and secondary manganese and uranium. In 1977, a grab sample assayed 12.3 per cent lead, 3.1 per cent zinc, 531.4 grams per tonne silver and 0.055 per cent uranium (Assessment Report 6776). Subsequent drilling intersected minor autunite and fluorite minerals, with the best assay being 0.016 per cent uranium over 1.2 metres (Assessment Report 6905).

Several springs in the area are high in radon. One sample measured 64,189 picocuries per litre radon (Assessment Report 6776). Soil samples in the area assayed up to 0.12 per cent uranium and 0.07 per cent thorium. Aquatic moss samples assayed up to 0.17 per cent uranium and 0.08 per cent thorium (Journal of Geochemical Exploration, 1981).

In 1977, an exploration program was conducted on parts of the Mir 1-7 claims by Union Oil Company of Canada Ltd. Grid controlled radiometric and geochemical surveys and prospecting work was completed in addition to follow-up geochemistry and reconnaissance scintillometry along the western Trout Lake graben margin. Work on the Mir property was done at intervals, being part of a larger program involving the Surprise Lake batholith and surrounding area. In 1978, three BQ diamond-drill holes totalling 449 metres were drilled on the Mir 3 and Mir 7 (104N 112) claims on behalf of Union Oil Company of Canada Ltd.

In 2006, Aldershot Resources Ltd. conducted a spectral analysis program on their Atlin East property which covers the CX (104N 114), Mir 3, 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.