Hemlo Gold Field

The biggest new gold field discovered in Canada in the 1980s gold boom was at Hemlo in Ontario, north of Lake Superior. Three mines, all within a mile, David Bell, Golden Giant and Williams, opened in 1985 and have produced between them close to 30 tonnes (2.9 million oz) annually ever since.

Headgear and the Mill of Williams mine,
Hemlo, largest mine in Canada
(Credit: Timothy Green)

The unique feature of the Hemlo field is that it is a very thinly disseminated orebody, originally averaging 9.5g/t (0.3 oz) although now reduced, sandwiched between sedimentary and volcanic rock. Ninety per cent of the reserves are in a single 'horizon' curving down from the surface to 1,500 metres (5,000 feet) along a strike length of two kilometres.

David Bell and Williams are jointly owned by Barrick (following Barrick's merger with Homestake in December 2001) and Teck, Golden Giant is now owned by Newmont Mining after their takeover of Battle Mountain in January 2001.