When Alexander Dadson began exploring the Yellowknife region in the early 1940s, he saw potential beyond the small, high-grade gold showings known to exist since 1898. Starting from the original discovery outcrop, he unraveled the complex geology and outlined minable zones on what was to become the biggest and richest gold deposit in the Northwest Territories. In 1998, the Giant mine passed the 50-year mark with a total output of about 7 million ounces.
Sixteen years later, Dadson confirmed his extraordinary ability as a geologist by guiding Lake Dufault Mines to the discovery of its Norbec and Millenbach polymetallic (copper-zinc-silver-gold) mines in the Noranda region of Quebec. During his illustrious career, spent mostly with Thayer Lindsley’s Ventures Ltd. and related companies, he remained modest about his many professional achievements. A quiet and generous man, he was frequently described as “one of the unsung heroes of mineral exploration in Canada.”
Dadson received his B.Sc (1932), M.Sc. (1933) and Ph.D. (1938) degrees from the University of Toronto. After graduation, he worked for Lindsley’s Frobisher Exploration, which had just taken control of Giant Yellowknife Gold Mines and was planning to test showings on the Giant property. Dadson’s geological examination in the summer of 1943 led to the concept that the drift-filled Baker Creek Valley, an area neglected by previous exploration, was underlain by a system of gold-bearing shear zones. Drilling began in 1944 and, in a matter of weeks, Dadson outlined a zone that later became part of the Giant mine. It was named the ASD zone in his honour. Ongoing work found other zones, which proved that Frobisher had made the deal of a lifetime.
Dadson’s geological knowledge and experience were used to great advantage by Ventures, which consisted of 180 separate companies. As chief geologist, Dadson helped consolidate these companies for a subsequent merger with Falconbridge Nickel Mines. This huge and complex task did not deter Dadson from keeping a strong hand in exploration, particularly on behalf of Lake Dufault Mines.
In 1958, Dadson recommended deep exploration of the Lake Dufault property. After the major program suggested by the property’s geologist was turned down because of diminishing resources, Dadson recommended that two deep holes be drilled. The reduced program began in 1961, and the first hole resulted in the discovery, that same year, of the Norbec orebody, near the location recommended by Dadson. Production began in 1964, and, some time later, drilling tested Dadson’s second target; this led to the discovery of the Millenbach mine in 1966. Production began in 1971, starting with the Dadson zone.