TSX retreats as lower commodity prices pressure resource stocks

TORONTO (Reuters) - Canada's main stock index fell on Tuesday as lower commodity prices weighed on the shares of materials and energy companies. - The Toronto Stock Exchange's S&P/TSX composite index <.GSPTSE> closed down 72.93 points, or 0.45 percent, at 16,298.88. - Losses for the index came as the recent rally on Wall Street paused. - The materials group, which includes precious and base metals miners and fertilizer companies, fell 1.2 percent, while the energy group retreated 1.9 percent. - The most influential weights included oil and gas producer Encana Corp , which fell 5 percent to C$16.72. Barrick Gold Corp declined 3.1 percent to C$18.88 and diversified miner Teck Resources Ltd was down 4.1 percent at C$37.06. - Gold slipped from a four-month high reached on Monday as the U.S. dollar clawed back some lost ground, while copper and nickel hit multi-week lows. Crude prices also pulled back after recent gains. - BlackBerry Ltd fell 1.7 percent to C$17.18 despite launching cyber-security software that identifies vulnerabilities in programs used in self-driving cars. - Eight of the index's 10 main groups ended lower. - Yellow Pages Ltd advanced 0.7 percent to C$8.27 after the company, once well known for its thick-print directories, said it would fire about 500 employees to cut costs and turn around its digital advertising platform. - SSR Mining Inc jumped 12.3 percent to C$11.48 after the precious metal miner reported fourth-quarter earnings and provided guidance for 2018. - Constellation Software Inc climbed 6.9 percent to C$787.87 after its Harris Operating Group acquired Acceo Solutions for C$250 million. (Reporting by Fergal Smith and Alastair Sharp; Editing by Bernadette Baum and Peter Cooney)