* TSX down 30.78 points, or 0.2 percent, to 14,993.75
* Five of the TSX's 10 main groups were down
TORONTO, Sept 8 (Reuters) - Canada's main stock index fell on Friday and was on track for its fifth straight day of declines, as mining and energy stocks dominated the retreat and with investors cautious over the impact of Hurricane Irma, which was headed toward Florida.
The five biggest drags on the index were mining stocks, with Teck Resources Ltd falling 4.1 percent to C$28.61 and First Quantum Minerals Ltd off 3.5 percent to C$13.81. Hudbay Minerals Inc plunged 11.4 percent to C$9.52 after the company announced a C$242 million bought deal financing.
The overall materials group lost 1.2 percent.
Cuba began shutting down its nickel industry in preparation for Hurricane Irma, while copper prices slipped on profit-taking as analysts said the recent price surge was not justified.
At 10:20 a.m. ET (1420 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 30.78 points, or 0.2 percent, to 14,993.75.
Half of the index's 10 key sectors were in the red.
The energy group retreated 0.8 percent, as U.S. crude prices fell due to low refining activity following Tropical Storm Harvey, which cut demand for oil to process.
Encana Corp was down 2.2 percent to C$11.36.
The heavily weighted financials group offset some of the losses with a modest rebound after losing more than 2 percent in the last week.
Declining issues outnumbered advancing ones on the TSX by 168 to 70, for a 2.40-to-1 ratio on the downside.
The index was posting 5 new 52-week highs and 3 new lows. (Reporting by Solarina Ho; Editing by Phil Berlowitz)