(Updates prices, adds sector details) March 29 (Reuters) - Canada’s main stock index fell on Monday, as energy and mining shares tracked subdued commodities, although optimism about an economic recovery capped losses. * The energy sector dropped 1.4%, while the materials sector, which includes precious and base metals miners and fertilizer companies, lost 0.7%. * At 9:50 a.m. ET (13:50 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 18.72 points, or 0.1%, at 18,733.86. * Miners SilverCrest Metals Inc and Endeavour Silver Corp down 4.4% and 3.6% respectively, were the biggest decliners on the index. * The financials sector slipped 0.2%, while the industrials sector rose 0.4%. * On the TSX, 85 issues were higher, while 143 issues declined for a 1.68-to-1 ratio to the downside, with 17.42 million shares traded. * The largest percentage gainers on the TSX were all-terrain vehicle maker BRP Inc, which climbed 3.7%, and pharmaceuticals OrganiGram Holdings Inc, which rose 3%. * The most heavily traded shares by volume were Bombardier Inc, Tamarack Valley Energy Ltd and ClearStream Energy Services Inc. * The TSX posted six new 52-week highs and no new lows. * Across all Canadian issues, there were 33 new 52-week highs and one new low, with total volume of 38.80 million shares. (Reporting by Amal S in Bengaluru)