The Sunbeam vein is located about 7.5 kilometres north-northeast of Stewart, near the headwaters of Dunwell Creek and approximately 1350 metres east of the Stewart highway (37A).

The area is underlain predominantly by north striking, west dipping argillites and siltstones of the Middle Jurassic Salmon River Formation (Hazelton Group) (Bulletin 58; 63). The contact with the underlying andesitic volcanics of the Lower Jurassic Unuk River Formation (Hazelton Group) lies about 300 metres to the west. The argillaceous sediments are intruded by north to northwest trending granodiorite and lamprophyre dikes. Several conspicuous north to north-northeast trending, west dipping faults traverse the area and belong to the Portland Canal fissure zone (Geological Survey of Canada Memoir 32). These faults are associated with precious metal veins in several locations in the immediate area. There are several en echelon, north to north-northeast trending, west dipping quartz veins exposed on the Sunbeam claim.

The Sunbeam vein is about 100 metres east of the portal of the Sunbeam adit. The north trending vein dips 40 to 50 degrees west and has been traced south from the boundary of the former Dandy 1 claim (104A 067) along Dunwell Creek for a distance of about 240 metres. The vein is 1.2 to 1.8 metres wide and carries pyrite, galena, sphalerite, tetrahedrite, argentite and native silver. Argentite and native silver locally occur as 20 centimetre wide streaks along the hangingwall of the vein. For much of the exposed length the vein is associated with a grey dike. The vein may split into two separate branches at the southern limit of the exposure.

The Sulphide vein (possibly the northern extension of the Dunwell vein) is about 60 metres east of the Sunbeam vein. The variably oxidized, 0.6 to 1.8 metre wide vein carries pyrite, galena and sphalerite. The vein, approximately parallel to the Sunbeam vein, dipping 50 degrees west, lies on the east side of a wide felsite dike.

Two veins were intersected in the Sunbeam adit, which was driven about 50 metres below the exposed Sunbeam vein. At 52 metres from the portal, a 0.6 metre wide zone of barren quartz veins and stringers occurs. At 91 metres from the portal, a 1.2 metre wide, sheared and brecciated siliceous zone is sparsely mineralized. It is not known whether these veins are the downdip extensions of the Sunbeam and Sulphide veins, respectively.

In 1981, a chip(?) sample collected from a vein, presumably in the Sunbeam adit, assayed 4.1 grams per tonne gold, 42.5 grams per tonne silver, 2.74 per cent lead and 1.06 per cent zinc across 20 centimetres (Assessment Report 10190). A grab sample from the adit(?) dump assayed 4.1 grams per tonne gold, 32.9 grams per tonne silver, 1.35 per cent lead and 4.70 per cent zinc (Assessment Report 10190).

The Sunbeam claim (Lot 869) was staked before 1907 by the Stewart brothers and Noble, who had carried out considerable exploration work. That year the Stewart Mining and Development Company acquired the claim. Nass River Lands subsequently acquired the property and the company was reorganized and became Dunwell Mines in 1922. The property was intermittently explored during 1922-41; most of the activity focused on the Dunwell mine, about 550 metres to the south (103P 052). Before 1937, at least four adits (the 150 metre long Sunbeam crosscut adit and three other short adits) and several opencuts had been emplaced on the mineralization. During 1932-33, about 100 tonnes of ore was high graded from pits on the exposed Sunbeam vein, this is likely included in the production figures for the Dunwell mine (Minister of Mines Annual Report 1937, page B8). During 1964-66, Silver Arrow Explorations Ltd. explored the property; results of the work are unknown. In 1979, Tournigan Mining Explorations Ltd. conducted geological mapping in the area. In 1981, Kingdom Resources Ltd. performed an exploration program on the MM 100 (104A 054) property to the north. The Sunbeam adit area was sampled that year. No further work has been reported on the showing.