Mirado Mine is a past producing underground gold mine located 35km SE of Kirkland Lake, and is easily accessible via road. Mirado is proximal to numerous operations including Macassa, Young-Davidson, Holt, Black Fox, and Westwood. Mirado deposit interpreted to be a gold rich VMS system with a gold-rich stringer footwall (South Zone) overlain by a zinc and gold-rich bedded hanging wall (North Zone).

Gold on the Mirado Gold Property was first discovered in the early 1920s and later mined by underground methods to a depth of 500′ in the 1940s. Several exploration programs, diamond drilling campaigns, and underground and open pit mining activities have taken place since then. Over the years, over 40,000m of drilling was completed by several companies, including Mirado Nickel Mines, Broulan Reef, Amax Minerals Exploration, and Golden Shield Resources Inc (Golden Shield). 

The previous work can be reviewed in historic reports on the Ontario government website, including an environmental base line study, bulk sampling, stockpiling of open pit and underground material, and metallurgical test-work programs. Golden Shield contracted Dynatec Mining Ltd. in 1986 for underground and open-pit operations. Much of the Mirado south zone was pre-stripped, and an open pit was mined to a depth of 30m. The material removed from the pit was stockpiled on the Mirado property, where it remains today.

Metallurgical test-work was undertaken under the supervision of A. S. Hayden of EH Associates in 1986. Settling and filtration tests were conducted, and Lakefield Research prepared test slurries. A study of three alternative metallurgical processes was undertaken, including (1) selective flotation with cyanidation of concentrate; (2) direct cyanidation of ore with Merrill- Crowe recovery; and (3) direct cyanidation of ore, with carbon in pulp gold recovery. Gold recoveries up to 95% were realized.