The Roanan showing is believed to be located on the Last Chance claim, previously known as the Olympia Extension claim, near Skookum Creek, approximately 1250 metres east of the Salmon River in south- eastern Alaska.

Located in the Intermontane Belt, the area, bounded on the west by the Coast Crystalline complex and on the east by the Bowser Basin, is part of the Stikinia Terrane.

The showing is hosted by the Upper Triassic to Lower Jurassic Hazelton Group Unuk River Formation metavolcanics. The Hazelton Group is a northwest trending steeply east dipping belt of folded andesitic lapilli tuffs, flows and breccia containing a thick sequence of argillite and siltstone infolded along a synclinal axis. The sequence is intruded by the Early Jurassic Texas Creek plutonic suite of dacitic porphyry dykes and sills, Eocene granitic Hyder intrusives and lamprophyre dykes.

The mineralized quartz vein is hosted in a Texas Creek porphyry dyke near the Unuk River Formation contact. The vein strikes 140 degrees, dips 45 degrees east and has been traced along strike for 183 metres. The vein has an average width of 1 metre and a vertical dimension of 76 metres. The walls of the vein show slickensiding. A surface trench exposed the vein 1.22 to 1.83 metres wide, mineralized with stringers of solid sulphides. Mineralization consists of tetrahedrite, galena, sphalerite, chalcopyrite and pyrite with associated gold and silver values. Tetrahedrite occurs in solid stringers up to 5 centimetres wide while other sulphides are layered. Ankerite and barite are associated with vein mineralization (probably alteration products).

The vein has been exposed underground along strike in 2 drifts. The vein in the upper drift contains several small crystals of scheelite. In the lower drift, the vein averages 30 centimetres in width and contains sparsely distributed grains of scheelite over a length of 15 metres with an estimated grade of 0.05 per cent scheelite (United States Geological Survey, Bulletin 1024-F).

A sample across 1.83 metres in the surface exposure, taken in 1917, assayed 48.68 grams per tonne gold and 349.74 grams per tonne silver (United States Geological Survey, Bulletin 807).

The Roanan and Olympia extension veins may be two separate veins in the same structure. Vague locational evidence suggests that they are the same vein, and have been described as such here.