The Yankee-Dundee project incorporates over 74 square kilometers of mineral claims in prolific and historic Southeast BC, a region that has produced over 5.6 million ounces of gold and over $70 billion in mineral wealth to date starting with placer mining in the 1850s and moving to lode mining in the 1880s.
Stillwater Critical Minerals (operating as Duncastle Gold Corp.) sold the Yankee-Dundee project to Armex Mining in early 2013 as announced in news releases on January 21 and June 25, 2013. Under the terms of the sale agreeement, Stillwater CM may receive $4-million or more by way of cash and royalty payments, depending on mine performance, commodity markets and other factors, including advance royalty payments.
The project comprises most of the historic Ymir Camp which was in the 1930s the largest silver producer in the British Commonwealth. The claims also include the largest mine in the camp, the Yankee Girl Mine. Despite the comparatively primitive methods of the day, the Yankee Girl was significant with 375,000 tonnes mined from over 14 levels between 1907 and 1951, yielding over $180 million in gross value at today’s prices. In addition to the Yankee Girl, the project includes over a dozen other past producing mines and countless mineralized showings. Despite its successful history, Southeast BC was underexplored for a number of years, held back in terms of mineral exploration by a combination of fractured land holdings, markets, politics, and commodity prices. The past few years have seen a turning point and a number of companies are now active in the area. Commodity prices, in particular gold, have brought a return of interest to the high-grade, high profit margin mines of the Kootenays.
Stillwater Critical Minerals was a relatively early entrant, as its founders commenced staking and acquisition in 2003 before acquiring the Yankee-Dundee crown grants in 2006. In keeping with its vision of building land positions covering and surrounding significant past producers, Stillwater CM assembled the more than 74 square kilometer claims package to examine the potential for larger mineralized systems as well as extensions of known systems through application of modern exploration methods in the first systematic programs conducted on the property.
Location, Access, Infrastructure
Located in the Nelson Mining District south of Nelson BC, the Yankee-Dundee is just 3 kilometers from the town of Ymir BC and 50 kilometers east of Teck’s smelter at Trail, BC. Infrastructure in terms of power and rail is excellent, and the mine is a few kilometers from Highway 6. Historically the Yankee Girl mine ran year-round.
The historic mine workings are expected to provide low-cost underground access and a rapid start-up to potential mining. One of these, the Wildhorse adit, a 1.4 kilometer exploration adit that reaches the Yankee Girl structure 110 meters below the workings, was completed in 1954 and inspected by Group Ten personal in 2006 and found to be in apparently sound structural condition. Also of interest is the 1235 adit, the main production adit, which is immediately below the Yankee Girl West zone identified in surface drilling.
There have been two focuses of exploration activity within the Yankee-Dundee project, with the historic Yankee Girl Mine and related high-grade vein structures being the primary focus. The more regional potential of the larger claim package is also being actively explored including data compilation and mapping work, prospecting (eg grab samples to 155g/t gold and 353g/t silver), soil geochem surveys (multiple anomalies), ground level geophysics, drilling and an airborne geophysical survey covering much of the property.
Yankee Girl Mine
Exploration of the Yankee Girl mine is summarized in the long section figure (below) showing five target “panels” of mineralization within the Yankee Girl structure. Surface drilling identified the Yankee Girl West zone in panel 3, which is one of five exploration target areas of similar or greater dimension. The historic mine workings are shown in panel 1.
Yankee Girl Mine Long Section
Stillwater Critical Minerals drilled 48 diamond drill holes totaling approximately 7,700 meters at the Yankee-Dundee project, with much of that work focused on the Yankee Girl West zone, a high-grade mineralized extension to the west of the Yankee-Girl mine. As shown in the Long Section figure, the Yankee Girl West zone is located immediately above the main production adit, the 1235 adit, and has good potential for low-cost production.
The Yankee Girl West zone was defined in 2009 as a continuous mineralized structure along the western projection of the Yankee Girl structure by combining the previously modeled higher-grade mineralized shoots, based on the strong continuity of gold and silver-enriched sulphide mineralization observed between them. Past reports by Stillwater Critical Minerals and others dating to 1934 referred to mineralized shoots, similar to the shoots mined between 1907 and 1951, along strike and to the west of the historic Yankee Girl mine. Drilling in 2009 demonstrated sufficient on-strike continuity of higher–grade mineralization to merge the previously referred to Yukon, 400 and 790 shoots into one larger mineralized zone which is now termed the Yankee Girl West zone (“YGW”). The drill-defined strike-length of the mineralized zone has expanded to some 285m along the western projection of the Yankee Girl structure. To date gold and silver-enriched polymetallic mineralization in the YGW has been drill tested to only 280 meters vertical depth where it reaches the historic mine workings (1235 level) and remains open at depth to the west below the 1235 level, and to the east towards the historic mine.
As tested to date, the mineralized portion of the Yankee Girl structure consists of a quartz breccia up to 7.8 meters estimated true thickness, containing massive sulphide horizons ranging up to 1.2 metres thick. Massive sulphide horizons contain clots and lenses of massive to finely banded sphalerite, galena, pyrite and locally pyrrhotite with scattered rounded quartz and minor host rock fragments with up to four massive sulphide horizons distributed within, or along the contacts of the quartz breccia.
Ymir Camp - General History
Gold mineralization was first reported near Ymir in the late 1800s, with much of the mining taking place at the Yankee Girl, Dundee and Ymir mines during the period 1907 to 1951.
The Ymir gold-silver camp was discovered in the late 1800s with production beginning at the Ymir, Dundee and Protection deposits in 1899. Production reached a peak in the 1930s and the camp was, during these years, the largest silver-producing camp in the British Commonwealth. Production from these deposits ceased in the early 1950s, with total production of 1.7 million ounces silver, 290,000 ounces gold, 14.1 million kgs lead, and 9.1 million kg zinc. (Production data was obtained from historical government records and has not been independently verified by the current operators of the project.)
The Dundee Mine was among the earliest discoveries in the Ymir Camp (1888), while the Yankee Girl mine, which would go on to become the biggest producer in the camp, was discovered in 1899. The Yankee Girl and Dundee mines were connected in 1940 to form the Yankee-Dundee Mine. Production from these deposits ceased in 1951.
Exploration work since shut-down was inconsistent and limited in scope until Stillwater Critical Minerals’ work in 2006, although some significant exploration work has been done since closure: in 1954 the Wildhorse Adit was extended to 1,417m in length and identified two new veins, the Cannon and the Bonus, before encountering the Yankee Girl vein. A raise was started on the Yankee Girl vein for 11 meters. In 1961 Cayzor Athabaska Mines Ltd drove a raise on the Yankee Girl Vein for 143.2 meters intersecting the 1625 Level.
The Wildhorse adit was inspected by Stillwater Critical Minerals personnel in May 2006 and found to be in apparently sound condition. It is expected to be a valuable asset in exploration as well in potential bulk sampling or mining activity.