The Theda Bara Nickel showing is located about 9.5 kilometres due south of Alice Arm near the headwaters of Roundy Creek. The area was investigated for base and precious metals during the 1920s and again during the 1960s. This showing is 204 metres south of the Theda Bara base metal vein showing (103P 157).

The region is underlain by Eocene Coast Plutonic Complex rocks intruding Middle Jurassic to Upper Cretaceous Bowser Lake Group argillite, shale, siltstone, greywacke and conglomerate. The sediments have been folded and altered to biotite hornfels.

A 1.2 to 1.5 metre wide quartz vein in argillite, 240 metres to the south of the adits, lies along a dioritic/gabbroic dike and strikes 030 degrees. The vein contains a near massive lens of pyrrhotite. Samples are reported to assay trace gold, 51 grams per tonne silver (Minister of Mines Annual Report 1924, page 51) and trace gold and silver, 0.25 per cent nickel (Minister of Mines Annual Report 1927, page 70).