By Fergal Smith
TORONTO, March 7 (Reuters) - Canada's main stock index fell on Wednesday as a drop in commodity prices weighed on resource shares, while steel producer Stelco Holdings Inc STLC.TO rallied on prospects for Canada to be exempted from proposed U.S. metals tariffs.
* The White House said Canada and Mexico, and possibly other countries, may be exempted from planned U.S. import tariffs onsteel and aluminum on the basis of national security. Stelco rose 3.9 percent to C$24.63. The stock had hit a nearly seven-week low on Tuesday at C$23.00.
* The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE closed down 72.58 points, or 0.47 percent, at15,472.61.
* The resignation of Gary Cohn, top economic adviser to U.S. President Donald Trump, intensified investor worries over a global trade war, while the Bank of Canada said trade policy is an "important and growing source of uncertainty." The materials group, which includes precious and base metals miners and fertilizer companies, lost 1.4 percent.
* Agnico Eagle Mines Ltd AEM.TO fell 2.0 percent toC$49.47 after Credit Suisse (SIX:CSGN) cut its price target on the stock.
* Gold futures GCc1 fell 0.2 percent to $1,326 an ounce,while U.S. crude oil futures CLc1 settled 2.3 percent lower at$61.15 a barrel. GOL/ O/R
* The energy group fell nearly 1 percent, with TransCanadaCorp TRP.TO down 2.3 percent at C$55.65.
* The shares of trade-sensitive auto parts and railroadcompanies lost ground. Magna International Inc MG.TO declined0.4 percent to C$67.66 and Canadian National Railway Co CNR.TO was down 0.7 percent at C$94.09.
* Great Canadian Gaming Corp GC.TO rose 12.4 percent toC$38.15 after reporting fourth-quarter results after the bell onTuesday.