* TSX down 40.14 points, or 0.32 percent, at 12,322.94
* Seven of its 10 main sectors finish lower (Updates with details, quotes)
TORONTO, Oct 4 (Reuters) - Toronto's main stock index closed lower on Monday as mining shares fell as metals prices dropped.
The TSX index's heavyweight materials sector, home to mining stocks, was the biggest loser, sinking 1 percent. Barrick Gold ABX.TO fell 1.8 percent to C$47.09 and Iamgold IMG.TO retreated 1.7 percent to C$17.66
Gold prices, which were at record highs last week, slipped as promising U.S. existing home sales data bolstered the U.S. dollar. [GOL/] [FRX] The U.S. dollar and gold usually move in opposition, due in part to the fact that gold is priced in U.S. dollars.
"I just think that we're backing and filling on the stocks," said John Ing, president of Toronto investment dealer Maison Placements, noting golds as a group hit a record high last week.
"I guess investors this week chose to take profits notwithstanding bullion was acting reasonably well," he said.
Also in the materials sector, Teck Resources TCKb.TO dropped 2.3 percent to C$42.34 as copper prices eased off two-year highs due to the firmer greenback. [MET/L]
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE closed down 40.14 points, or 0.32 percent, at 12,322.94. Seven of the index's 10 TSX subgroups ended lower.
The TSX index hit a two-year high on Friday.
($1=$1.02 Canadian) (Reporting by Solarina Ho and Cameron French; editing by Peter Galloway)