Marceau told reporters after speaking to the Montreal board of trade that the government's objective is to "respect the principles" of the party's campaign pledge.
But when pressed about whether the increases will result in as much new revenue as promised in the party platform, the minister said: "It depends on the choice we made."
He said that the government will make "calculations and estimates" and that the final increase in royalties will result in "significant increases" in government revenues.
In its platform, the PQ vowed to enact a mandatory minimum royalty of five per cent on the gross value of production and to tax up to 30 per cent on the "excess profits" of mining companies — that is profit above what is normally earned.
Marceau said Friday that the definition of "excess profits" required "conceptual work" by the Finance Department.
The government plans to consult the mining industry and others over the coming months before putting the royalty plan in place next year.