Nearly 30,000 people are in Toronto for the Prospectors and Developers Association of Canada convention, billed as the biggest mining convention in the world.
The event's growing size shows how the mining industry is booming around the globe and in Ontario.
The convention attracts ten times the number of people it did in the early 1990s, when many considered mining to be an industry on the decline.
Mining minister Rick Bartolucci told the convention that annual exploration spending in Ontario surpassed $1 billion last year, five times higher than in 2003.
Driven largely by demand from China, commodity prices continue to rise, fuelling the mining boom.
And it's being felt far from where the digging happens.
Ross Gallinger heads the Prospectors and Developers Association of Canada.
"Toronto is the financial hub for this business, you have many mining companies headquartered here,” Gallinger said.
But the recent Drummond report, which studied ways for the province to pare back spending, said Ontario’s mining tax credits are too generous and should be reviewed
Chris Hodgson, president of the Ontario Mining Association, said mining companies will not invest in Ontario if they can't turn a profit quickly.
"Don't change the rules on this industry midstream," he said.
Last year, the convention drew more than 27,000 people.