The Toronto Stock Exchange's S&P/TSX rose 22.70 points, or 0.14 percent, to 16,510.82.
Leading the index were CannTrust Holdings Inc , up 19.2 percent, Peyto Exploration & Development Corp , up 6.2 percent, and Nuvista Energy Ltd , higher by 6.1 percent.
Lagging shares were Transcontinental Inc , down 8.5 percent, Cameco Corp, down 7.8 percent, and Nexgen Energy Ltd, lower by 7.8 percent.
On the TSX 138 issues rose and 97 fell as a 1.4-to-1 ratio favored advancers. There were 12 new highs and 6 new lows, with total volume of 147.4 million shares.
The most heavily traded shares by volume were Canntrust Holdings Inc , Encana Corp and Toronto-dominion Bank.
The TSX's energy group fell 0.60 points, or 0.4 percent, while the financials sector slipped 0.11 points, or 0.0 percent.
West Texas Intermediate crude futures fell 1.54 percent, or $0.93, to $59.28 a barrel. Brent crude fell 0.88 percent, or $0.59, to $66.13.
The TSX is up 15.3 percent for the year.
