The A Vein, which is located 800 metres north-northeast of the Big Missouri deposit, lies within south-southeast striking, moderately dipping andesite, agglomerate and lapilli tuff, with interbedded cherty tuff of the Lower Jurassic Unuk River Formation. (See Big Missouri (104B 046) for enhanced geology).

The A Vein, which strikes east and dips 60 degrees south, occurs in a 12.2 to 15.2 metre wide shear zone which cross-cuts a north-trending altered zone (see Unicorn (104B 044)). The occurrence lies immediately west of the north trending Union Creek Fault. The vein is cut by southeast-striking lamprophyre dykes.

Mineralization is erratic and consists of disseminated pyrite, sphalerite, and galena, with reports of visible gold in quartz. A composite grab sample along the vein assayed 4.8 grams per tonne gold and 463 grams per tonne silver (Cochrane, 1974).

In 2009, resampling of the A Vein trenches by Ascot Resources yielded good assay results. In 2010, Ascot targeted 2 drillholes on the A Vein which Ascot included in the central portion of the Unicorn zone (104B 044). It is located at a flat area along the creek where previous operators identified a small outcrop of mineralization in several trenches. Drill hole P10-056 was located on the same pad as P10-055 but oriented south and oriented to target the A-Vein. A small zone was encountered at the top of the hole, 0.27 gram per tonne gold over 10.98 metres, and the rest of the hole was largely in a fault with a mix of broken up andesite and minor silica altered andesite plus clay altered (faulted) andesite (Assessment Report 32357). The presence of the fault (Union Creek Fault) in the gully is supported by the results of the drill hole but little mineralization that could be associated with the A-vein showing was encountered.

See Unicorn (104B 044), Big Missouri (104B 046) and Premier (104B 054) for related details of the Dilworth and Premier properties that were held as a single entity in the 2000s by Boliden Ltd and Ascot Resources.