The Iron Mask property occurs near the northern edge of the Late Triassic-Early Jurassic Iron Mask batholith. The Iron Mask and Erin orebodies were of similar shape, size and attitude. Each was lens shaped in plan and about 53 metres in horizontal length. Their widths were fairly similar; including low grade ore; the Erin orebody generally did not exceed 9 metres, while the Iron Mask orebody attained a maximum width at lower depths of more than 6 metres. Both orebodies strike 065 degrees. The mine plans show that both orebodies dip about 75 degrees to the southeast, and that the Erin orebody dips less steeply above the 91 metre level. Stope outlines of both orebodies are lenticular above the 183 metre level. At this level the Erin orebody splits eastward. The Iron Mask orebody continued to 210 metres slope depth, where it is reported to have been cut off by a low angle fault. The footwall of each orebody is recorded as well defined and the hangingwall as indefinite.

About 23 metres west of the Iron Mask shaft, mineralized diorite in contact with picrite basalt has been mined to within 2.4 metres of the surface. The exposed contact is irregular in detail, being essentially breccia of mineralized white rock and unmineralized picrite basalt. It strikes about 055 degrees and dips 60 degrees southeast. Chalcopyrite occurs as disseminations and stringers. Iron oxide is abundant in a small vein in the northern wall of the breccia zone. At the shaft itself, a mineralized fault zone in diorite 1.5 metres wide strikes 060 degrees and dips at about 60 degrees to the southeast. The footwall of this zone is poorly defined and contains another mineralized zone that dips at 35 degrees to the southwest.

There is little record of the mineralogy of the Iron Mask ore. On the dump, the only mineralized material seen is diorite carrying disseminated chalcopyrite. Ore mined in 1923 was stated to carry pyrite. The reported association of gypsum and talc in fracture planes in diorite near the bottom of the Iron Mask shaft is similar to the Larsen workings (092INE011). Gypsum gangue occurred in one of the late developed orebodies in the eastern workings. The oxidized material of the Erin orebody contained chalcopyrite with some malachite, azurite and cuprite. A little bornite was seen on the dump. The Erin orebody was oxidized at least to the 30 metre level. On the 183 metre level about 100 metres north of the Erin shaft station, a vein 35 centimetres wide was followed 137 metres in a drift. In 1928, production was principally from an orebody about 274 metres northwest of the Erin orebody. It was worked on the 228 metre level to a width of 3.6 metres, a length of 36.5 metres and a height of 27.4 metres. Much of the material was low in grade.

The greater part of the production was from the Iron Mask orebody, and, in addition to the Iron Mask and Erin orebodies, smaller ones were worked south and east of the Iron Mask shaft. Mining was by shrinkage stoping; some of the ore was hand sorted for direct shipment.

The Iron Mask shaft is located on the north side of Iron Mask hill, about 8 kilometres west of Kamloops; the Erin shaft lies about 396 metres to the northeast and the Norma shaft about 548 metres to the north. The Iron Mask showing was staked in August 1896 by G. Breedsen, W.H. Ford and R.H. Loyn. The Erin showing was staked shortly thereafter by a Mr. Beattie and associates. By 1898 the Erin shaft had been sunk to 29 metres and several crosscuts driven. The Norma shaft (092INE011) is on Lot 1066 (Erin Fr.) about 244 metres south of the Larsen shaft (092INE011). This shaft is sunk vertically to a single level 61 metres below the collar. A raise connects this level with the Iron Mask 228 metre level, which is estimated to be 49 metres lower in elevation. The Iron Mask, Erin and Norma workings are interconnected. The Iron Mask was bonded to The B.C. Exploring Syndicate, Limited, of London, England, and subsequently disposed of to the Cole Hill Gold, Silver and Copper Mining Company, Limited. The Iron Mask (Lot 878), Sunrise (Lot 879), Bonnie Jean (Lot 850) and Copper Queen (Lot 880) were Crown granted to the company in 1900. Shaft sinking and drifting were in progress and in 1903 a 100 ton-per-day concentrator was completed. The company was reorganized in 1904 under the name Kamloops Mines, Limited, and the Erin and adjacent claims were bonded. The concentrator was expanded to 200 tons-per-day and operations continued into 1908. The property, comprising some 16 claims and fractions, was purchased in 1909 by E.G. Wallinder and associates, of Duluth, who incorporated the Kamloops Copper Company. The mine was reopened in 1910. A new 150 ton-per-day mill was built in 1917 and expanded to 300 tons-per-day in 1918. The operation became unprofitable and the mine closed in 1920. To that date the underground workings totalled over 4877 metres. The Iron Mask shaft, inclined at 68 degrees, was sunk to 238 metres and seven levels established, the lowest at 229 metre slope depth below the collar. The Erin shaft, inclined at 70 degrees, was sunk to 100 metres and levels established at vertical depths of 30 and 91 metres. A raise connecting the 228 metre level of the Iron Mask with the 91 metre level of the Erin was completed in about 1916. The mine reopened in 1922 but was forced to close in 1924 due to financial difficulties. The company was then reorganized under the name Continental Copper Co., Limited, with head office in Chicago. The mine was reopened in 1925 and a program of underground exploration began. The Norma shaft was sunk to a single level 61 metres below the collar; a raise was driven from the Iron Mask 228 metre level to connect with this level. From 1925 until November 1928 when the mine closed, extensive development work was accompanied by some production, largely from smaller orebodies. After World War II quantities of explosives were jettisoned in the Iron Mask and Erin shafts, wrecking and caving the collars. The Iron Mask and Erin claims were acquired in about 1946 by W.A. Urquhart, G.F. Dickson and associates. Kamloops Copper Company Ltd. was incorporated in October 1951 to acquire some 40 claims and fractions, including most of the original Iron Mask holdings. In 1952, the property was optioned to Berens River Mines Limited and an electromagnetic survey carried out. Further electromagnetic surveying was done in 1956 over an area measuring 4877 by 1829 metres that extends immediately north of the Iron Mask shaft. The mine was dewatered in 1961 and about 3352.8 metres of diamond drilling completed in the old workings. The company name was changed in 1964 to Kamloops Copper Consolidated Ltd. Vanco Explorations Limited held an option on the property in 1965-66 and some geophysical work was carried out. Kamloops Copper in 1972 amalgamated with Midland Petroleums, Ltd. and Consolidated Prudential Mines Ltd. to form Davenport Oil & Mining Ltd. In March 1972, the property was optioned to Comet Industries Ltd. In December 1972, Getty Mining Pacific, Limited optioned 120 contiguous claims in the combined properties (Victor, 092INE011, Iron Mask, Iron Cap, 092INE018 and DM, 092INE030) held by Comet, Initial and Davenport. Work by Getty in 1973 included an induced polarization survey over 93.3 line kilometres, a magnetometer survey over 86.9 line kilometres, 2084.5 metres of rotary drilling in 8 holes, 564.4 metres of diamond drilling in 2 holes, and 15,513.4 metres of percussion drilling in 159 holes. Among these holes, 25 were spaced over a 3.2 by 4.8 kilometre area. The option was given up in 1974. Davenport Oil & Mining changed its name in 1973 to Davenport Industries Ltd. Initial Developers Corporation in May 1974 amalgamated with North Pacific Mines Ltd. under the name Initial Developers Limited. Canadian Superior Exploration Limited optioned the above combined properties (some 2185 hectares) in 1975. Work in 1976-78 included a magnetometer survey over 89 line kilometres, 8064 metres of diamond drilling in 47 holes and 4211 metres of percussion drilling in 48 holes. The option was terminated in 1978. Craigmont Mines Limited in February 1981 obtained an exploration agreement on the above four properties and on the adjacent Rainbow property (092INE028) of Pacific Seadrift Resources. Work by Craigmont included diamond drilling, mainly on the Victor and Rainbow properties. This work indicated insufficient tonnage and the option was terminated in September 1981. In 1986, the property was owned by Comet Industries Ltd. (40 per cent), Davenport Industries Ltd. (30 per cent) and Initial Developers Limited (30 per cent). Work over the Iron Mask and/or adjacent ground in 1983 included 13 kilometres of geophysical surveys and 294 metres of drilling to further delineate reserves; an additional 400 metres of drilling was reported in 1986; drilling may have been in part on the "Tailing Zone". Teck Corporation and Metall Mining Corporation, through Afton Operating Corporation, in August 1987 obtained from Comet, Davenport and Initial a 10 year exploration option (to earn a 75 per cent interest if production is achieved) on the Iron Mask and adjacent properties comprising 25 Crown grants, ten two-post claims, and 8 located claims (86 units).