TORONTO, March 7 (Reuters) - Canada's main stock index retreated on Tuesday as lower commodity prices weighed on mining and energy shares, while industrials and financials also lost ground.
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE unofficially closed down 20.97 points, or 0.13 percent, at 15,608.78. Eight of the index's 10 main groups ended lower.