O'Brien is a former mining town in northeastern Ontario near Gowganda with a warm-summer humid continental (Dfb) Köppen climate classification. The mining town serviced several mines including silver mines around nearby lake Miller Lake; one of the past-producing silver mines was Ontario's largest producing Cobalt-style silver mine outside of Cobalt, with historical production of 40.7 million ounces of silver between 1910 and 1972.
References