The S&P/TSX composite index fell 16.58 points to 14,290.54 in early trading.
Meanwhile, the loonie was up 0.30 of a cent at 77.00 cents US after posting its lowest closing price in more than a decade.
The September contract for crude oil was up 27 cents at US$49.46, while the August natural gas contract was down 0.1 of a cent at US$2.896.
The August gold contract was up US$3 at US$1,094.50.
In the U.S., the Dow Jones industrial average fell 13.09 points to 17,837.95, while the Nasdaq climbed 12.34 points to 5,184.11. The S&P 500 gained 1.42 points to 2,115.57.