The Yankee Girl mine is located on the north side of Oscar Creek, 3 kilometres east-northeast of Ymir. The nearby Dundee property was one of the first to be developed in the Ymir area. Gold was initially discovered on the Yankee Girl in 1899. The Yankee Girl and Dundee (082FSW067) mines were amalgamated in 1940. A crosscut was developed from the Yankee Girl 1235 level to connect with the Dundee adit. The Dundee vein occurs 300 metres to the south.

The area is underlain by Jurassic Ymir Group slate, argillite and argillaceous quartzites intruded by granodiorite of the Middle to Late Jurassic Nelson Intrusions. The contact with a southern tongue of the Nelson batholith crosscuts the area. The area is strongly faulted with the faults forming a conjugate set. One set hosts mineralized veins.

The Yankee Girl vein, averaging 1.5 metres in width, has a maximum width of 9 metres with productive sections never wider than 4 metres. The vein fissure, striking 060 to 070 degrees and dipping 55 to 70 degrees south, hosts quartz gangue with fragments of brecciated and altered granodiorite and schist. Mineralization consists of pyrite, galena and sphalerite with values in gold, silver and cadmium. The values are erratically distributed. Ore occurs in well-defined shoots which generally rake to the east. The Spur vein, equally rich, branches off the Yankee Girl vein on the footwall and is parallel to it for 250 metres.

The Lakeview cataclastic zone/vein is the largest mineralized fault on the property. Average gold values from drifting on the vein at the Yankee Girl junction were 3.4 grams per tonne gold (Assessment Report 14719). The Lakeview zone, more than 15 metres wide, exhibits intense deformation, banding, flow characteristics and brecciation. Fractures are filled with quartz and mineralized with disseminated and irregular masses of pyrite and minor disseminated sphalerite. The zone is hosted in granitic rocks varying in composition from granite to diorite. Argillic alteration is common. Drilling on the Lakeview zone in 1985 was disappointing.

Two other mineralized veins, the Bonus (120 metres north of the Yankee Girl) and Cannon veins, were identified in the Wildhorse crosscut in 1954. The Bonus vein is parallel to the Yankee Girl. A sample taken from a section of the Bonus vein, where it is 2 metres wide, assayed 15.43 grams per tonne gold, 9.94 grams per tonne silver, 2.65 per cent zinc and 1.2 per cent lead (Assessment Report 14719). A sample across 1 metre in the Cannon vein averaged 13.0 grams per tonne gold (George Cross News Letter No.145, 1988).

Production from the Yankee Girl and parallel veins totalled 370,616 tonnes with a grade of approximately 8.6 grams gold and 44.5 grams silver per tonne. Lead constitutes an average of 1.5 per cent and zinc assays about 2.8 per cent.

Kingsvale Resources Ltd. optioned the property in 1988 and conducted trenching and sampling; they dropped the option in 1989.

The property is located at approximately 1097.2 metres elevation on the north side of Oscar Creek, 1.6 kilometres east of Ymir.

The Yankee Girl, Canadian Girl, and Atlin claims were staked in October 1899 by Messrs. Graham, Grobe, McLeod, Masterton, and Lovell. Development work was done in a series of open cuts, a shaft, and an adit ("Overland Tunnel") which gained a depth of 15 metres on the vein. In 1904 the Atlin and adjacent Nome and Yukon claims were held by Pat Daly, A. Parr, Wm. Coffey and associates. The Atlin-Nome workings included a shaft to 18 metres with a 15-metre crosscut to the north, and a 96-metre crosscut adit and drifts on the vein. On the Yukon claim an adit had been driven 75 metres. The Yankee Girl (Lot 7712) and Canadian Girl (Lot 7072) were Crown-granted in 1907 to David Grobe, Donald McLeod, James Cronin, and Eber Moore. The Yukon Fr. (Lot 5303) was Crown- granted to Messrs. Daly, Coffey, Hughes and Ryan. In 1910 the Atlin (Lot 4800) and Atlin Fr. No. 2 (Lot 9336) were Crown- granted to William Coffey.

The property was bonded in 1907 by a syndicate of American interests. About 305 metres of development work was carried out and a tram line was built from the Yukon claim to the wagon road. The bond was given up in August of that same year. Early in 1908 the property was bonded by H.L. Rodgers, representing New York interests, and developnent work began in driving the 1235 (No. 4) level adit from the Old Bill claim of the adjacent Dundee property (82 F/6, Au 10). Operations were transferred to Yankee Girl Gold Mines, Limited which was incorporated in South Dakota and registered in British Columbia in 1909.

The Yankee Girl, Canadian Girl and Yukon Fraction were optioned in 1911 by Hobson Silver-Lead Company, Limited of Spokane, which was controlled by Fort Worth Texas interests. An aerial tram 1829 metres long was built from the 1235 level to the railroad at Ymir. Development work continued in the 1235 level and ore was shipped to smelters at Greenwood, Grand Forks, and Trail, the high silica content of the ore making it desirable for fluxing purposes. The company ceased operations in 1919. Ownership of the property was transferred to Texas Yankee Girl Mines, Limited, which was registered in British Columbia in 1920.

The Mining Corporation of Canada, Limited optioned the property in the spring of 1920 and carried out 628 metres of drifting and crosscutting and 204.2 metres of raising in known areas of the mine. The option was given up later in the year. No further activity was reported until 1926 when O.C. Thompson and associates optioned the property and incorporated Yankee Girl, Limited. The mine was reopened and some ore shipped during the year. In May 1927 The Porcupine Goldfields Development and Finance Company, Limited optioned the property. Further development work was carried out and diamond drilling was done to test for ore below the 1235 level. Enterprise Consolidated Mining Company, Limited optioned the property in March 1928 from Texas Yankee Girl Mines, Limited. The company name Enterprise) was changed to Yankee Girl Consolidated Mines, Limited. Further development work was done in the upper levels of the mine. The workings at that time included 2 shafts, 5 adits and 10 levels totalling some 5486 metres of openings. In the fall of 1928 a new crosscut adit was begun on the Ymir (Wildhorse) Creek side of the mountain 233 metres below the 1235 level. When work was suspended late in 1929 the Wildhorse adit had been driven 869 metres.

Early in 1933 E.P. Crawford, F.R. Weekes and associates took over the property under an agreement with Texas Yankee Girl Mines, Limited and incorporated Ymir Yankee Girl Gold Mines, Limited in May 1934. The property included 5 Crown-granted claims, the Yankee Girl, Canadian Girl, Lakeview, Black Diamond, Yukon Fr., and Klondyke No. 1 Fr. The company installed a 100 t.p.d. mill which began production in January 1935. A winze was sunk to 91 metres below the 1235 level, extending the workings to a depth of 495 metres and comprising eleven levels. The company continued operations during 1938 while lessees carried out the mining of ore remnants in pillars and stopes in the less accessible parts of the mine. In 1939 the company carried out a salvage mining operation in pillars and stope remnants. A crosscut adit was driven from the 1235 adit level to the Dundee ore zone in 1940. The mill operated on Dundee ore, and on mill tailings from former operations, until June 1942 when the company ceased work. Lessees operated the mill until near the end of the year, treating backfill from old stopes. Lessees continued intermittent mining and clean up operations into 1950.

Yankee Dundee Mines Limited was incorporated in November 1952 to develop the Yankee Girl and Dundee properties. Rehabilitation and extension of the Wildhorse adit began and in 1954 the adit reached a length of 1417 metres. At 1247 metres from the portal the Bonus vein was intersected and drifted on for 20 metres. At 1417 metres the Yankee Girl vein was encountered and drifted on for 14 metres. In December 1954 a raise was started on the vein but only driven 11 metres when work stopped.

Newmont Mining Corporation of Canada Limited optioned the property in August 1960. Diamond drilling was done in 2 holes to test the Bonus vein. The option was given up in December.

Cayzar Athabaska Mines Limited in August 1961 optioned the property from Yankee Dundee and drove a raise on the Yankee Girl vein for 143.5 metres to intersect the old workings at the 1625 level. Drifting totalling 126 metres and some 678 metres of diamond drilling in 5 holes was done on the Yankee Girl vein from the Wildhorse adit. The option was given up in 1965. The company name (Yankee Dundee) was changed in 1963 to Dundee Mines Limited.

Burlington Mines Ltd. by an agreement dated July 1966 acquired from Dundee Mines 24 Crown-granted claims. Rehabilitation and maintenance work was done in the Wildhorse adit. The company name was changed to Burlington Mines & Enterprises Ltd. in 1970 and to Burlington Gold Mines Ltd. in 1974.