The Iron Mask showing is on the north side of Smelter Lakes, 1 kilometre east of the Similkameen River and 10.5 kilometres south of Princeton.

This Crown-granted claim is underlain by microdiorite, micromonzonite and microsyenite of the Early Jurassic Lost Horse Intrusions to the east and by diorite of the Early Jurassic Smelter Lake Stock (Copper Mountain Intrusions) to the west.

A series of trenches and shafts is reported to have exposed a body of iron-rich mineralization (magnetite breccia ?), carrying minor gold values (Minister of Mines Annual Report 1908, page 128).