The Toronto Stock Exchange's S&P/TSX fell 8.40 points, or 0.05 percent, to 16,502.42.
Leading the index were First Majestic Silver Corp , up 8.4 percent, Pan American Silver Corp , up 6.4 percent, and First Quantum Minerals Ltd , higher by 6.2 percent.
Lagging shares were Turquoise Hill Resources Ltd , down 43.2 percent, NFI Group Inc, down 10.3 percent, and CannTrust Holdings Inc, lower by 9.5 percent.
On the TSX 98 issues rose and 138 fell as a 0.7-to-1 ratio favored decliners. There were 12 new highs and 4 new lows, with total volume of 177.9 million shares.
The most heavily traded shares by volume were Turquoise Hill Resources Ltd , Encana Corp and Bombardier Inc.
The TSX's energy group fell 2.26 points, or 1.6 percent, while the financials sector slipped 0.05 points, or 0.0 percent.
West Texas Intermediate crude futures fell 2.55 percent, or $1.52, to $58.06 a barrel. Brent crude fell 2.33 percent, or $1.55, to $64.93.
The TSX is up 15.2 percent for the year.