The Centre Star, War Eagle and Le Roi claims, located at the northwestern edge of the city of Rossland, formed the nucleus of a property that was subsequently expanded by the Consolidated Mining and Smelting Company of Canada Limited (Cominco) to include some 30 claims and fractions. The Iron Mask and War Eagle claims were reportedly developed by the Tar Eagle Gold Mining Company, and from about 1897 by the War Eagle Consolidated Mining & Development Company, Limited. The Centre Star, War Eagle and Iron Mask mines were acquired by Cominco in 1906.

Cominco purchased the adjoining Josie property in 1923. By 1928 when the company closed the mine the original workings had all been connected underground to form one large mine with a total of about 97 kilometres of underground workings; mining operations were carried on to a depth of about 503 metres.

Groups of lessees, sometimes over 30 in number, extracted remnants of ore from the old surface and underground workings from 1932 until the company closed down the operation in June 1942; Cominco carried out a program of geological mapping during 1940-1941.

In May 1967 Hunstone Ventures Ltd. obtained an option from Cominco on 72 Crown-granted claims, including the mine workings of the Le Roi, Centre Star, War Eagle, Iron Mask, Josie, Kootenay Columbia, Nickel Plate, and Crown Point claims. By an agreement of August 1, 1967, Hunstone assigned the agreement to Falaise Lake Mines Ltd. During 1967-1968 Falaise carried out 3194 metres of surface diamond drilling, in 41 holes in the hanging wall of the Le Roi, Centre Star, and War Eagle veins, and magnetometer and electromagnetic surveys over other parts of the property. Based on this drilling, together with the work by Cominco in 1940, the indicated ore reserves in pillars and stope remnants in the upper part of the Le Roi, Iron Mask, and War Eagle workings were estimated at 278,800 tonnes averaging 7 grams per tonne gold, 20.9 grams per tonne silver, and 0.65 per cent copper. In May 1969 an adit was begun at the north edge of the Golden-Born Crown-grant (Lot 1234) and directed towards the 800 level crosscut of the Le Roi workings. The adit, driven for 1310 metres, was completed in October 1970. Underground diamond drilling was carried on into 1971. The option was subsequently dropped.

The Iron Mask mine is hosted by the Rossland monzonite and the Rossland sill. The Rossland monzonite is an east trending stock which intrudes an augite porphyry sill of the Lower Jurassic Elise Formation (Rossland Group), known as the Rossland sill.

The deposit is part of the "Main vein" system of the Rossland camp which forms a continuous well defined fracture system on a regional scale trending 70 degrees for a strike length in excess of 1.0 kilometre. The Iron Mask deposit is a mineralized cross structure, a zone of enrichment at the intersection of the Iron Mask and Centre Star north veins (082FSW094). Sulphide mineralization consists of the replacement of wallrock along well defined fractures and infilling the fractures or fault system with pyrrhotite, chalcopyrite, and pyrite. Gangue consists mainly of altered wallrock with minor lenses of quartz and calcite.

A vertical shaft driven in 1896 contained high grade ore which averaged 78.86 grams per tonne gold (Geological Survey of Canada Memoir 77, page 103). BC production records show production for the Iron Mask from 1898 to 1901 and again in 1904 when a total of 14,218 tonnes were mined from which 448,059 grams of gold, 434,019 grams of silver and 189,328 kilograms of copper were recovered. The Iron Mask was historically part of the Centre Star-War Eagle Group (082FSW094 and 082FSW097) and other production data may be combined with one of these occurrences.

Refer to the Le Roi deposit (082FSW093) for details of the regional geology and Main vein-type deposit characteristics.