The Prospectors and Developers Association of Canada (PDAC) represents the interests of the Canadian mineral exploration and development industry. The association was established in 1932 in response to a proposed government regulation that threatened the livelihood of Ontario prospectors. The William (Bill) W. Dennis Prospector of the Year Award is presented to individuals or groups who have made a significant mineral discovery, offered noteworthy contributions to the PDAC, or have been involved in some important service or technological invention or innovation that helped improve the Canadian prospecting and exploration industry.
Alex Mosher came from a family that has been mining and prospecting in Canada for three generations. Although born in 1900 at the Eureka Gold Mine in Nova Scotia, Alex grew up and started is prospecting career in Cobalt.
In 1927, with his brother Murdock, he staked the Central Patricia gold mines. He played a key part in staking the Ashley Gold Mines in the Matachewan area in 1930. The following year, again along with his brother, staked a bloc of claims during the Little Long Lac staking rush that later became the Mosher Long Lac Gold Mines.
He participated in the first gold discovery in Yellowknife in 1938.
He also located and staked the first radioactive vein in 1947 at Otter Rapids on the Abitibi River, the first of its kind outside of the Northwest Territories, discovered the iron-ore Griffith Mine at Bruce Lake in 1953, in Northwestern Ontario, and the Chimo Gold Mines in Quebec in the mid-sixties.
During 1967 and 1968, Mr. Mosher was president of PDAC and together with W.W. Denis gave guidance and support to the Association in its early struggle to stay alive and effective. He was also inducted into the Canadian Mining Hall of Fame in 1990.