By John Tilak TORONTO, Jan 23 (Reuters) - Canada's main stock index fell on Wednesday, led by gold stocks, which slid with the price of the precious metal, and miner Iamgold Corp slipped after it gave a production forecast. Gold prices declined as progress in talks about the U.S. debt limit dimmed the precious metal's appeal as a safe haven. Republican leaders in the House of Representatives said they aim to pass on Wednesday a nearly four-month extension of the U.S. debt limit, and the White House welcomed the move. The Toronto index eased from an 18-month high it hit earlier in the session. "The market is a little topsy-turvy. There's a lot of indecision out there. People are nervous," said Irwin Michael, portfolio manager at ABC Funds. The Toronto Stock Exchange's S&P/TSX composite index was down 20.36 points, or 0.16 percent, at 12,804.27. Seven of the 10 main sectors of the index were down. Earlier in the session, the index briefly turned positive to touch 12,828.93, its highest since Aug. 2, 2011. "One of the big dilemmas for investors is, 'is this all for real?'," Michael said. "People were worried about the fiscal cliff, now they are worrying about the debt ceiling. The market continues to climb this wall of worry." The materials sector, which includes mining stocks, fell 0.5 percent, tracking the decline in gold prices. The group played the biggest role of any single sector in leading the market lower. Miner Goldcorp Inc slipped 0.8 percent to C$37.71. Shares of fellow miner Iamgold fell 9 percent to C$9.79, a day after the company gave a production forecast. The financial sector, the index's weightiest, was down 0.2 percent. Royal Bank of Canada gave back 0.5 percent to C$61.44, and Toronto Dominion Bank lost 0.6 percent to C$82.99. The energy sector offset some of the weakness, rising 0.02 percent, as oil prices gained.