The Toronto Stock Exchange's S&P/TSX fell 152.19 points, or 0.92 percent, to 16,371.28.
Leading the index were Torex Gold Resources Inc, up 3.2 percent, Seven Generations Energy Ltd, up 3.1 percent, and Bombardier Inc, higher by 2.7 percent.
Lagging shares were Shopify Inc, down 9.0 percent, MAG Silver Corp, down 6.4 percent, and Osisko Gold Royalties Ltd, lower by 5.3 percent.
On the TSX 42 issues rose and 194 fell as a 0.2-to-1 ratio favored decliners. There were 13 new highs and 2 new lows, with total volume of 206.7 million shares.
The most heavily traded shares by volume were Barrick Gold Corp, Bombardier Inc and Kinross Gold Corp.
The TSX's energy group fell 0.91 points, or 0.6 percent, while the financials sector slipped 1.68 points, or 0.5 percent.
West Texas Intermediate crude futures fell 0.1 percent, or $0.06, to $57.84 a barrel. Brent crude rose 0.29 percent, or $0.19, to $65.05 [O/R]
The TSX is up 14.3 percent for the year.