* TSX down 4.16 points, or 0.03 percent, at 12,442.70 * Financials, base metal miners push lower * Gold miners lead materials sector higher By Alastair Sharp TORONTO, Sept 18 (Reuters) - Canada's benchmark stock index slipped slightly on Tuesday as declines in the prices of commodities other than gold hurt base metal miners and energy companies, and attention shifted from the U.S. Federal Reserve stimulus to underlying economic troubles. Both crude oil and copper were down from multi-month highs hit last week after the U.S. Federal Reserve said it would buy $40 billion a month of mortgage-backed securities bonds, a move known as quantitative easing, as it sought to improve the U.S. labor market outlook. Gold, however, remained buoyant as the precious metal is typically viewed as a hedge against inflation. The market is reflecting both exuberance after the Fed stimulus and worry that a looming "fiscal cliff" - expiring tax cuts and U.S. government spending reductions due early next year - will derail the economy of Canada's main trading partner, according to Morgan Meighen & Associates Vice President Julie Brough. "You've got two dueling forces taking place in the market," she said. "We're going back and forth - OK, now we have liquidity but are we going to have the corporate earnings if we don't have economic growth?" By 10:44 a.m. (1444 GMT) the Toronto Stock Exchange's S&P/TSX composite index was down 4.16 points, or 0.03 percent, at 12,442.70. The index hit a five-month high on Friday. Penn West Petroleum Ltd was one of the biggest weights, down 2.9 percent at C$15.50, while Pacific Rubiales Energy Corp gained 2.9 percent to C$25.11. The materials sector - which includes precious and base metals miners as well as fertilizer companies - was up slightly, with most of the gains seen in the gold components. Financial stocks were among the worst-performing sectors, with insurers Sun Life Financial Inc and Manulife Financial Corp down 1.4 percent and 0.8 percent respectively. National Bank Financial upgraded a string of gold and base metal miners, saying the Fed's stimulus reduced the risk of deflation and boosted demand for bullion. "As with past bullion price increases, we believe the easier money to be made is by investing early," the bank's mining analysts said in a note to clients. Their top picks included Kinross Gold Corp, AuRico Gold Inc and Golden Star Resources Ltd.