Below is what the Government of Northwest Territories is thinking

"Likely prospects for near term development include:

• De Beers, Gahcho Kue - diamonds
• Tyhee, Yellowknife Gold Project
• Fortune Minerals, NICO Project - gold, cobalt, bismuth
• Avalon Resources, Thor Lake - rare earth metals"

Above exerpt from one of the websites belonging to the government's Department of Industry Tourism and Investment. Some other interesting reading on the site as well.

http://www.investnwt.ca/economic-sectors/mining