2020-8-11 · Richest gold mines in the world. Source: Mines and Metals. 1. Macassa, Canada. 22.1 g/t Au. Macassa gold mine, Canada. Source: Kirkland Lake. Richest gold mine measured by gold grade in reserves is Macassa underground gold mine, Ontario, Canada, owned by Kirkland Lake Gold. Macassa is part of one of Canada''s oldest and richest systems.